Merge m-c to inbound, a=merge

MozReview-Commit-ID: 7XpmaFg1k8N
2017-08-29 16:17:13 -07:00 · 2017-08-29 16:17:13 -07:00 · a8e6d0bd2c
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@ -467,10 +467,12 @@ pref("browser.tabs.drawInTitlebar", false);
 pref("browser.tabs.drawInTitlebar", true);
 #endif

-// false - disable the tabbar session restore button
-// true - enable the tabbar session restore button
-// To be enabled with shield
-pref("browser.tabs.restorebutton", false);
+// 0 - Disable the tabbar session restore button.
+// 1 - Enable the tabbar session restore button.
+// 2 - Control group. The tabbar session restore button is disabled,
+// but we will record data on other session restore usage.
+// To be enabled with shield.
+pref("browser.tabs.restorebutton", 0);

 // When tabs opened by links in other tabs via a combination of
 // browser.link.open_newwindow being set to 3 and target="_blank" etc are
--- a/browser/base/content/browser-sync.js
+++ b/browser/base/content/browser-sync.js
@ -492,7 +492,7 @@ var gSync = {

    let broadcaster = document.getElementById("sync-status");
    broadcaster.setAttribute("syncstatus", "active");
-    broadcaster.setAttribute("label", this.syncStrings.GetStringFromName("syncing2.label"));
+    broadcaster.setAttribute("label", this.syncStrings.GetStringFromName("syncingtabs.label"));
    broadcaster.setAttribute("disabled", "true");
  },

--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@ -8285,15 +8285,22 @@ function switchToTabHavingURI(aURI, aOpenNew, aOpenParams = {}) {

 var RestoreLastSessionObserver = {
  init() {
+    let browser_tabs_restorebutton_pref = Services.prefs.getIntPref("browser.tabs.restorebutton");
+    Services.telemetry.scalarSet("browser.session.restore.browser_tabs_restorebutton", browser_tabs_restorebutton_pref);
+    Services.telemetry.scalarSet("browser.session.restore.browser_startup_page", Services.prefs.getIntPref("browser.startup.page"));
    if (SessionStore.canRestoreLastSession &&
        !PrivateBrowsingUtils.isWindowPrivate(window)) {
-      if (Services.prefs.getBoolPref("browser.tabs.restorebutton")) {
+      if (browser_tabs_restorebutton_pref == 1) {
        let {restoreTabsButton, restoreTabsButtonWrapperWidth} = gBrowser.tabContainer;
        let restoreTabsButtonWrapper = restoreTabsButton.parentNode;
        restoreTabsButtonWrapper.setAttribute("session-exists", "true");
        gBrowser.tabContainer.updateSessionRestoreVisibility();
        restoreTabsButton.style.maxWidth = `${restoreTabsButtonWrapperWidth}px`;
        gBrowser.tabContainer.addEventListener("TabOpen", this);
+        Services.telemetry.scalarSet("browser.session.restore.tabbar_restore_available", true);
+        restoreTabsButton.addEventListener("click", () => {
+          Services.telemetry.scalarSet("browser.session.restore.tabbar_restore_clicked", true);
+        });
      }
      Services.obs.addObserver(this, "sessionstore-last-session-cleared", true);
      goSetCommandEnabled("Browser:RestoreLastSession", true);
--- a/browser/base/content/test/sync/browser_sync.js
+++ b/browser/base/content/test/sync/browser_sync.js
@ -198,7 +198,7 @@ function checkSyncNowButton(buttonId, syncing, tooltip = null) {

  is(remoteTabsButton.hasAttribute("disabled"), syncing, "disabled has the right value");
  if (syncing) {
-    is(remoteTabsButton.getAttribute("label"), gSync.syncStrings.GetStringFromName("syncing2.label"), "label is set to the right value");
+    is(remoteTabsButton.getAttribute("label"), gSync.syncStrings.GetStringFromName("syncingtabs.label"), "label is set to the right value");
  } else {
    is(remoteTabsButton.getAttribute("label"), gSync.syncStrings.GetStringFromName("syncnow.label"), "label is set to the right value");
  }
--- a/browser/components/extensions/test/browser/browser-common.ini
+++ b/browser/components/extensions/test/browser/browser-common.ini
@ -52,6 +52,7 @@ skip-if = (os == 'win' && !debug) # bug 1352668
 [browser_ext_browsingData_localStorage.js]
 [browser_ext_browsingData_pluginData.js]
 [browser_ext_browsingData_serviceWorkers.js]
+[browser_ext_chrome_settings_overrides_home.js]
 [browser_ext_commands_execute_browser_action.js]
 [browser_ext_commands_execute_page_action.js]
 [browser_ext_commands_execute_sidebar_action.js]
@ -157,7 +158,6 @@ skip-if = debug || asan # Bug 1354681
 [browser_ext_themes_icons.js]
 [browser_ext_themes_validation.js]
 [browser_ext_url_overrides_newtab.js]
-[browser_ext_url_overrides_home.js]
 [browser_ext_user_events.js]
 [browser_ext_webRequest.js]
 [browser_ext_webNavigation_frameId0.js]
--- a/browser/components/extensions/test/browser/browser_ext_chrome_settings_overrides_home.js
+++ b/browser/components/extensions/test/browser/browser_ext_chrome_settings_overrides_home.js
@ -13,33 +13,69 @@ const HOME_URI_2 = "http://example.com/";
 const HOME_URI_3 = "http://example.org/";
 const HOME_URI_4 = "http://example.net/";

+const CONTROLLABLE = "controllable_by_this_extension";
+const CONTROLLED_BY_THIS = "controlled_by_this_extension";
+const CONTROLLED_BY_OTHER = "controlled_by_other_extensions";
+
 add_task(async function test_multiple_extensions_overriding_home_page() {
  let defaultHomePage = Preferences.get("browser.startup.homepage");

-  let ext1 = ExtensionTestUtils.loadExtension({
-    manifest: {"chrome_settings_overrides": {}},
-    useAddonManager: "temporary",
-  });
+  function background() {
+    browser.test.onMessage.addListener(async msg => {
+      switch (msg) {
+        case "checkHomepage":
+          let homepage = await browser.browserSettings.homepageOverride.get({});
+          browser.test.sendMessage("homepage", homepage);
+          break;
+        case "trySet":
+          await browser.browserSettings.homepageOverride.set({value: "foo"});
+          browser.test.sendMessage("homepageSet");
+          break;
+        case "tryClear":
+          await browser.browserSettings.homepageOverride.clear({});
+          browser.test.sendMessage("homepageCleared");
+          break;
+      }
+    });
+  }

-  let ext2 = ExtensionTestUtils.loadExtension({
-    manifest: {"chrome_settings_overrides": {homepage: HOME_URI_2}},
+  let extObj = {
+    manifest: {
+      "chrome_settings_overrides": {},
+      permissions: ["browserSettings"],
+    },
    useAddonManager: "temporary",
-  });
+    background,
+  };

-  let ext3 = ExtensionTestUtils.loadExtension({
-    manifest: {"chrome_settings_overrides": {homepage: HOME_URI_3}},
-    useAddonManager: "temporary",
-  });
+  let ext1 = ExtensionTestUtils.loadExtension(extObj);

-  let ext4 = ExtensionTestUtils.loadExtension({
-    manifest: {"chrome_settings_overrides": {homepage: HOME_URI_4}},
-    useAddonManager: "temporary",
-  });
+  extObj.manifest.chrome_settings_overrides = {homepage: HOME_URI_2};
+  let ext2 = ExtensionTestUtils.loadExtension(extObj);
+
+  extObj.manifest.chrome_settings_overrides = {homepage: HOME_URI_3};
+  let ext3 = ExtensionTestUtils.loadExtension(extObj);
+
+  extObj.manifest.chrome_settings_overrides = {homepage: HOME_URI_4};
+  let ext4 = ExtensionTestUtils.loadExtension(extObj);
+
+  extObj.manifest.chrome_settings_overrides = {};
+  let ext5 = ExtensionTestUtils.loadExtension(extObj);
+
+  async function checkHomepageOverride(ext, expectedValue, expectedLevelOfControl) {
+    ext.sendMessage("checkHomepage");
+    let homepage = await ext.awaitMessage("homepage");
+    is(homepage.value, expectedValue,
+       `homepageOverride setting returns the expected value: ${expectedValue}.`);
+    is(homepage.levelOfControl, expectedLevelOfControl,
+       `homepageOverride setting returns the expected levelOfControl: ${expectedLevelOfControl}.`);
+  }

  await ext1.startup();

  is(Preferences.get("browser.startup.homepage"), defaultHomePage,
     "Home url should be the default");
+  await checkHomepageOverride(ext1, null, CONTROLLABLE);

  // Because we are expecting the pref to change when we start or unload, we
  // need to wait on a pref change.  This is because the pref management is
@ -51,9 +87,22 @@ add_task(async function test_multiple_extensions_overriding_home_page() {
  ok(Preferences.get("browser.startup.homepage").endsWith(HOME_URI_2),
     "Home url should be overridden by the second extension.");

+  await checkHomepageOverride(ext1, HOME_URI_2, CONTROLLED_BY_OTHER);
+
+  // Verify that calling set and clear do nothing.
+  ext2.sendMessage("trySet");
+  await ext2.awaitMessage("homepageSet");
+  await checkHomepageOverride(ext1, HOME_URI_2, CONTROLLED_BY_OTHER);
+
+  ext2.sendMessage("tryClear");
+  await ext2.awaitMessage("homepageCleared");
+  await checkHomepageOverride(ext1, HOME_URI_2, CONTROLLED_BY_OTHER);
+
  // Because we are unloading an earlier extension, browser.startup.homepage won't change
  await ext1.unload();

+  await checkHomepageOverride(ext2, HOME_URI_2, CONTROLLED_BY_THIS);
+
  ok(Preferences.get("browser.startup.homepage").endsWith(HOME_URI_2),
     "Home url should be overridden by the second extension.");

@ -64,12 +113,16 @@ add_task(async function test_multiple_extensions_overriding_home_page() {
  ok(Preferences.get("browser.startup.homepage").endsWith(HOME_URI_3),
     "Home url should be overridden by the third extension.");

+  await checkHomepageOverride(ext3, HOME_URI_3, CONTROLLED_BY_THIS);
+
  // Because we are unloading an earlier extension, browser.startup.homepage won't change
  await ext2.unload();

  ok(Preferences.get("browser.startup.homepage").endsWith(HOME_URI_3),
     "Home url should be overridden by the third extension.");

+  await checkHomepageOverride(ext3, HOME_URI_3, CONTROLLED_BY_THIS);
+
  prefPromise = promisePrefChangeObserved("browser.startup.homepage");
  await ext4.startup();
  await prefPromise;
@ -77,6 +130,7 @@ add_task(async function test_multiple_extensions_overriding_home_page() {
  ok(Preferences.get("browser.startup.homepage").endsWith(HOME_URI_4),
     "Home url should be overridden by the third extension.");

+  await checkHomepageOverride(ext3, HOME_URI_4, CONTROLLED_BY_OTHER);

  prefPromise = promisePrefChangeObserved("browser.startup.homepage");
  await ext4.unload();
@ -85,12 +139,18 @@ add_task(async function test_multiple_extensions_overriding_home_page() {
  ok(Preferences.get("browser.startup.homepage").endsWith(HOME_URI_3),
     "Home url should be overridden by the third extension.");

+  await checkHomepageOverride(ext3, HOME_URI_3, CONTROLLED_BY_THIS);
+
  prefPromise = promisePrefChangeObserved("browser.startup.homepage");
  await ext3.unload();
  await prefPromise;

  is(Preferences.get("browser.startup.homepage"), defaultHomePage,
     "Home url should be reset to default");
+
+  await ext5.startup();
+  await checkHomepageOverride(ext5, null, CONTROLLABLE);
+  await ext5.unload();
 });

 const HOME_URI_1 = "http://example.com/";
--- a/browser/components/extensions/test/xpcshell/test_ext_url_overrides_newtab.js
+++ b/browser/components/extensions/test/xpcshell/test_ext_url_overrides_newtab.js
@ -37,44 +37,92 @@ function awaitEvent(eventName) {
 }

 add_task(async function test_multiple_extensions_overriding_newtab_page() {
-  const NEWTAB_URI_1 = "webext-newtab-1.html";
-  const NEWTAB_URI_2 = "webext-newtab-2.html";
+  const NEWTAB_URI_2 = "webext-newtab-1.html";
+  const NEWTAB_URI_3 = "webext-newtab-2.html";
  const EXT_2_ID = "ext2@tests.mozilla.org";
+  const EXT_3_ID = "ext3@tests.mozilla.org";
+
+  const CONTROLLABLE = "controllable_by_this_extension";
+  const CONTROLLED_BY_THIS = "controlled_by_this_extension";
+  const CONTROLLED_BY_OTHER = "controlled_by_other_extensions";
+
+  function background() {
+    browser.test.onMessage.addListener(async msg => {
+      switch (msg) {
+        case "checkNewTabPage":
+          let newTabPage = await browser.browserSettings.newTabPageOverride.get({});
+          browser.test.sendMessage("newTabPage", newTabPage);
+          break;
+        case "trySet":
+          await browser.browserSettings.newTabPageOverride.set({value: "foo"});
+          browser.test.sendMessage("newTabPageSet");
+          break;
+        case "tryClear":
+          await browser.browserSettings.newTabPageOverride.clear({});
+          browser.test.sendMessage("newTabPageCleared");
+          break;
+      }
+    });
+  }
+
+  async function checkNewTabPageOverride(ext, expectedValue, expectedLevelOfControl) {
+    ext.sendMessage("checkNewTabPage");
+    let newTabPage = await ext.awaitMessage("newTabPage");
+
+    if (expectedValue) {
+      ok(newTabPage.value.endsWith(expectedValue),
+         `newTabPageOverride setting returns the expected value ending with: ${expectedValue}.`);
+    } else {
+      equal(newTabPage.value, expectedValue,
+            `newTabPageOverride setting returns the expected value: ${expectedValue}.`);
+    }
+    equal(newTabPage.levelOfControl, expectedLevelOfControl,
+          `newTabPageOverride setting returns the expected levelOfControl: ${expectedLevelOfControl}.`);
+  }
+
+  let extObj = {
+    manifest: {
+      "chrome_url_overrides": {},
+      permissions: ["browserSettings"],
+    },
+    useAddonManager: "temporary",
+    background,
+  };
+
+  let ext1 = ExtensionTestUtils.loadExtension(extObj);
+
+  extObj.manifest.chrome_url_overrides = {newtab: NEWTAB_URI_2};
+  extObj.manifest.applications = {gecko: {id: EXT_2_ID}};
+  let ext2 = ExtensionTestUtils.loadExtension(extObj);
+
+  extObj.manifest.chrome_url_overrides = {newtab: NEWTAB_URI_3};
+  extObj.manifest.applications.gecko.id =  EXT_3_ID;
+  let ext3 = ExtensionTestUtils.loadExtension(extObj);

  equal(aboutNewTabService.newTabURL, "about:newtab",
     "Default newtab url is about:newtab");

  await promiseStartupManager();

-  let ext1 = ExtensionTestUtils.loadExtension({
-    manifest: {"chrome_url_overrides": {}},
-    useAddonManager: "temporary",
-  });
-
-  let ext2 = ExtensionTestUtils.loadExtension({
-    manifest: {
-      "chrome_url_overrides": {newtab: NEWTAB_URI_1},
-      applications: {
-        gecko: {
-          id: EXT_2_ID,
-        },
-      },
-    },
-    useAddonManager: "temporary",
-  });
-
-  let ext3 = ExtensionTestUtils.loadExtension({
-    manifest: {"chrome_url_overrides": {newtab: NEWTAB_URI_2}},
-    useAddonManager: "temporary",
-  });
-
  await ext1.startup();
  equal(aboutNewTabService.newTabURL, "about:newtab",
       "Default newtab url is still about:newtab");

+  await checkNewTabPageOverride(ext1, null, CONTROLLABLE);
+
  await ext2.startup();
-  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_1),
+  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_2),
     "Newtab url is overriden by the second extension.");
+  await checkNewTabPageOverride(ext1, NEWTAB_URI_2, CONTROLLED_BY_OTHER);
+
+  // Verify that calling set and clear do nothing.
+  ext2.sendMessage("trySet");
+  await ext2.awaitMessage("newTabPageSet");
+  await checkNewTabPageOverride(ext1, NEWTAB_URI_2, CONTROLLED_BY_OTHER);
+
+  ext2.sendMessage("tryClear");
+  await ext2.awaitMessage("newTabPageCleared");
+  await checkNewTabPageOverride(ext1, NEWTAB_URI_2, CONTROLLED_BY_OTHER);

  // Disable the second extension.
  let addon = await AddonManager.getAddonByID(EXT_2_ID);
@ -83,39 +131,46 @@ add_task(async function test_multiple_extensions_overriding_newtab_page() {
  await disabledPromise;
  equal(aboutNewTabService.newTabURL, "about:newtab",
        "Newtab url is about:newtab after second extension is disabled.");
+  await checkNewTabPageOverride(ext1, null, CONTROLLABLE);

  // Re-enable the second extension.
  let enabledPromise = awaitEvent("ready");
  addon.userDisabled = false;
  await enabledPromise;
-  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_1),
+  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_2),
     "Newtab url is overriden by the second extension.");
+  await checkNewTabPageOverride(ext2, NEWTAB_URI_2, CONTROLLED_BY_THIS);

  await ext1.unload();
-  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_1),
+  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_2),
     "Newtab url is still overriden by the second extension.");
+  await checkNewTabPageOverride(ext2, NEWTAB_URI_2, CONTROLLED_BY_THIS);

  await ext3.startup();
-  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_2),
+  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_3),
   "Newtab url is overriden by the third extension.");
+  await checkNewTabPageOverride(ext2, NEWTAB_URI_3, CONTROLLED_BY_OTHER);

  // Disable the second extension.
  disabledPromise = awaitEvent("shutdown");
  addon.userDisabled = true;
  await disabledPromise;
-  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_2),
+  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_3),
   "Newtab url is still overriden by the third extension.");
+  await checkNewTabPageOverride(ext3, NEWTAB_URI_3, CONTROLLED_BY_THIS);

  // Re-enable the second extension.
  enabledPromise = awaitEvent("ready");
  addon.userDisabled = false;
  await enabledPromise;
-  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_2),
+  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_3),
   "Newtab url is still overriden by the third extension.");
+  await checkNewTabPageOverride(ext3, NEWTAB_URI_3, CONTROLLED_BY_THIS);

  await ext3.unload();
-  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_1),
+  ok(aboutNewTabService.newTabURL.endsWith(NEWTAB_URI_2),
     "Newtab url reverts to being overriden by the second extension.");
+  await checkNewTabPageOverride(ext2, NEWTAB_URI_2, CONTROLLED_BY_THIS);

  await ext2.unload();
  equal(aboutNewTabService.newTabURL, "about:newtab",
--- a/browser/components/migration/FirefoxProfileMigrator.js
+++ b/browser/components/migration/FirefoxProfileMigrator.js
@ -1,6 +1,6 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
- * vim: sw=2 ts=2 sts=2 et */
- /* This Source Code Form is subject to the terms of the Mozilla Public
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sw=2 ts=2 sts=2 et */
+/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

@ -131,7 +131,7 @@ FirefoxProfileMigrator.prototype._getResourcesInternal = function(sourceProfileD
  let favicons = getFileResource(types.HISTORY, ["favicons.sqlite"]);
  let cookies = getFileResource(types.COOKIES, ["cookies.sqlite"]);
  let passwords = getFileResource(types.PASSWORDS,
-    ["signons.sqlite", "logins.json", "key3.db",
+    ["signons.sqlite", "logins.json", "key3.db", "key4.db",
     "signedInUser.json"]);
  let formData = getFileResource(types.FORMDATA, [
    "formhistory.sqlite",
--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@ -1018,6 +1018,11 @@ BrowserGlue.prototype = {

  // All initial windows have opened.
  _onWindowsRestored: function BG__onWindowsRestored() {
+    if (this._windowsWereRestored) {
+      return;
+    }
+    this._windowsWereRestored = true;
+
    BrowserUsageTelemetry.init();
    BrowserUITelemetry.init();

--- a/browser/components/sessionstore/SessionStore.jsm
+++ b/browser/components/sessionstore/SessionStore.jsm
@ -3414,6 +3414,10 @@ var SessionStoreInternal = {
    tabstrip.smoothScroll = smoothScroll;

    TelemetryStopwatch.finish("FX_SESSION_RESTORE_RESTORE_WINDOW_MS");
+    if (Services.prefs.getIntPref("browser.tabs.restorebutton") != 0 ) {
+      Services.telemetry.scalarAdd("browser.session.restore.number_of_tabs", winData.tabs.length);
+      Services.telemetry.scalarAdd("browser.session.restore.number_of_win", 1);
+    }

    this._setWindowStateReady(aWindow);

--- a/browser/installer/windows/nsis/stub.nsi
+++ b/browser/installer/windows/nsis/stub.nsi
@ -1573,6 +1573,7 @@ Function LaunchApp
  ${If} $0 <> 0 ; integer comparison
    StrCpy $FirefoxLaunchCode "1"
    MessageBox MB_OK|MB_ICONQUESTION "$(WARN_MANUALLY_CLOSE_APP_LAUNCH)"
+    Call SendPing
    Return
  ${EndIf}
 !endif
--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@ -1607,9 +1607,14 @@ Element::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
    // Unset this flag since we now really are in a document.
    UnsetFlags(NODE_FORCE_XBL_BINDINGS |
               // And clear the lazy frame construction bits.
-               NODE_NEEDS_FRAME | NODE_DESCENDANTS_NEED_FRAMES);
-    // And the restyle bits
-    UnsetRestyleFlagsIfGecko();
+               NODE_NEEDS_FRAME | NODE_DESCENDANTS_NEED_FRAMES |
+               // And the restyle bits. These shouldn't even get set if we came
+               // from a Servo-styled document, but they may be set if the
+               // element comes from a Gecko-backed document, see bug 1394586.
+               //
+               // TODO(emilio): We can remove this and assert we don't have any
+               // of them when we remove the old style system.
+               ELEMENT_ALL_RESTYLE_FLAGS);
  } else if (IsInShadowTree()) {
    // We're not in a document, but we did get inserted into a shadow tree.
    // Since we won't have any restyle data in the document's restyle trackers,
@ -1617,9 +1622,10 @@ Element::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
    //
    // Also clear all the other flags that are cleared above when we do get
    // inserted into a document.
-    UnsetFlags(NODE_FORCE_XBL_BINDINGS |
-               NODE_NEEDS_FRAME | NODE_DESCENDANTS_NEED_FRAMES);
-    UnsetRestyleFlagsIfGecko();
+    //
+    // See the comment about the restyle bits above, it also applies.
+    UnsetFlags(NODE_FORCE_XBL_BINDINGS | NODE_NEEDS_FRAME |
+               NODE_DESCENDANTS_NEED_FRAMES | ELEMENT_ALL_RESTYLE_FLAGS);
  } else {
    // If we're not in the doc and not in a shadow tree,
    // update our subtree pointer.
--- a/ipc/mscom/VTableBuilder.h
+++ b/ipc/mscom/VTableBuilder.h
@ -8,7 +8,7 @@
 #define mozilla_mscom_VTableBuilder_h

 #include <stdint.h>
-#include <Unknwn.h>
+#include <unknwn.h>

 #if defined(__cplusplus)
 extern "C" {
--- a/layout/inspector/tests/chrome/test_parseStyleSheetObservers.html
+++ b/layout/inspector/tests/chrome/test_parseStyleSheetObservers.html
@ -65,24 +65,31 @@ function test1Result() {
 let foundImport = false;
 let foundStyle = false;
 let styleFirstAddProcessor = function(event) {
-  info("styleFirstAddProcessor: called");
+  info("styleFirstAddProcessor: called with event "+ event.rule.cssText);
  if (event.rule.type == CSSRule.IMPORT_RULE) {
    foundImport = true;
  } else if (event.rule.type == CSSRule.STYLE_RULE) {
    foundStyle = true;
    is(foundImport, false, "Test 2: The style rule arrived before the import rule.");
  }
-}
+  return foundImport;
+};

 async function test2Setup() {
  info("test2Setup: called");

-  DOMUtils.parseStyleSheet(sheet, "@import url('imported_no_op.css'); p { color: purple; }");
+  // Create a Promise to watch for two StyleRuleAdded events. The first invocation should
+  // be the style rule, and the second should be the import rule. We use the same processor
+  // for both events, but the processor will only return true (completing the Promise) when
+  // the import rule has been processed.
+  let gotAllStyleRuleAddedEvents = ContentTaskUtils.waitForEvent(document,
+    "StyleRuleAdded", true, styleFirstAddProcessor);
+
+  DOMUtils.parseStyleSheet(sheet, "@import url('imported_no_op.css'); p {color: purple;}");
  is(sheet.cssRules.length, 2, "Test 2: Stylesheet now has 2 rules.");

-  // Await and then process the 2 events we expect to arrive.
-  styleFirstAddProcessor(await ContentTaskUtils.waitForEvent(document, "StyleRuleAdded", true));
-  styleFirstAddProcessor(await ContentTaskUtils.waitForEvent(document, "StyleRuleAdded", true));
+  // Await and then process the events we expect to arrive.
+  await gotAllStyleRuleAddedEvents;

  is(foundStyle, true, "Test 2: Got the style rule.");
  is(foundImport, true, "Test 2: Got the import rule.");
--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@ -2832,9 +2832,14 @@ Gecko_ReportUnexpectedCSSError(ErrorReporter* reporter,
    }
  }

-  nsDependentCSubstring paramValue(param, paramLen);
-  nsAutoString wideParam = NS_ConvertUTF8toUTF16(paramValue);
-  reporter->ReportUnexpectedUnescaped(message, wideParam);
+  if (param) {
+    nsDependentCSubstring paramValue(param, paramLen);
+    nsAutoString wideParam = NS_ConvertUTF8toUTF16(paramValue);
+    reporter->ReportUnexpectedUnescaped(message, wideParam);
+  } else {
+    reporter->ReportUnexpected(message);
+  }
+
  if (suffix) {
    reporter->ReportUnexpected(suffix);
  }
--- a/layout/style/crashtests/1386773.html
+++ b/layout/style/crashtests/1386773.html
@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset=UTF-8>
+<style>
+::-moz-selection{}
+</style>
+<script>
+window.onload = () => {
+  r = document.createRange()
+  document.getSelection().addRange(r)
+  r.setEndAfter(document.body)
+}
+</script>
+</head>
+<body>A</body>
+</html>
--- a/layout/style/crashtests/crashtests.list
+++ b/layout/style/crashtests/crashtests.list
@ -199,6 +199,7 @@ load 1383981-2.html
 load 1383981-3.html
 load 1384824-1.html
 load 1384824-2.html
+load 1386773.html
 load 1387481-1.html
 load 1387499.html
 load 1388234.html
--- a/layout/style/test/gtest/StyloParsingBench.cpp
+++ b/layout/style/test/gtest/StyloParsingBench.cpp
@ -13,10 +13,12 @@

 using namespace mozilla;
 using namespace mozilla::css;
+using namespace mozilla::dom;
 using namespace mozilla::net;

 #define PARSING_REPETITIONS 20
 #define SETPROPERTY_REPETITIONS (1000 * 1000)
+#define GETPROPERTY_REPETITIONS (1000 * 1000)

 #ifdef MOZ_STYLO

@ -91,4 +93,36 @@ MOZ_GTEST_BENCH(Stylo, Servo_DeclarationBlock_SetPropertyById_WithInitialSpace_B
  ServoSetPropertyByIdBench(NS_LITERAL_CSTRING(" 10px"));
 });

+static void ServoGetPropertyValueById() {
+  RefPtr<RawServoDeclarationBlock> block = Servo_DeclarationBlock_CreateEmpty().Consume();
+  RefPtr<URLExtraData> data = new URLExtraData(
+    NullPrincipalURI::Create(), nullptr, NullPrincipal::Create());
+  NS_NAMED_LITERAL_CSTRING(css_, "10px");
+  const nsACString& css = css_;
+  Servo_DeclarationBlock_SetPropertyById(
+    block,
+    eCSSProperty_width,
+    &css,
+    /* is_important = */ false,
+    data,
+    ParsingMode::Default,
+    eCompatibility_FullStandards,
+    nullptr
+  );
+
+  for (int i = 0; i < GETPROPERTY_REPETITIONS; i++) {
+    DOMString value_;
+    nsAString& value = value_;
+    Servo_DeclarationBlock_GetPropertyValueById(
+      block,
+      eCSSProperty_width,
+      &value
+    );
+    ASSERT_TRUE(value.EqualsLiteral("10px"));
+  }
+}
+
+MOZ_GTEST_BENCH(Stylo, Servo_DeclarationBlock_GetPropertyById_Bench, ServoGetPropertyValueById);
+
+
 #endif
--- a/layout/style/test/mochitest.ini
+++ b/layout/style/test/mochitest.ini
@ -189,6 +189,7 @@ skip-if = toolkit == 'android' #bug 536603
 [test_css_escape_api.html]
 [test_css_function_mismatched_parenthesis.html]
 [test_css_loader_crossorigin_data_url.html]
+[test_css_parse_error_smoketest.html]
 [test_css_supports.html]
 [test_css_supports_variables.html]
 [test_default_bidi_css.html]
--- a/layout/style/test/test_css_parse_error_smoketest.html
+++ b/layout/style/test/test_css_parse_error_smoketest.html
@ -0,0 +1,53 @@
+<!doctype html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Test for CSS parser reporting parsing errors with expected precision</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" href="/tests/SimpleTest/test.css">
+</head>
+<body>
+<style id="testbench"></style>
+<script>
+  var tests = [
+    { css: "@unknown {}", error: "Unrecognized at-rule or error parsing at-rule ‘@unknown’." },
+
+    { css: "x { color: invalid; }", error: "Expected color but found ‘invalid’.  Error in parsing value for ‘color’.  Declaration dropped." },
+
+    { css: "::unknown {}", error: "Unknown pseudo-class or pseudo-element ‘unknown’.  Ruleset ignored due to bad selector." },
+    { css: ":unknown {}", error: "Unknown pseudo-class or pseudo-element ‘unknown’.  Ruleset ignored due to bad selector." },
+    { css: "::5 {}", error: "Expected identifier for pseudo-class or pseudo-element but found ‘5’.  Ruleset ignored due to bad selector." },
+    { css: ": {}", error: "Expected identifier for pseudo-class or pseudo-element but found ‘ ’.  Ruleset ignored due to bad selector." },
+
+    { css: "x[a.]{}", error: "Unexpected token in attribute selector: ‘.’.  Ruleset ignored due to bad selector." },
+    { css: "x[*a]{}", error: "Expected ‘|’ but found ‘a’.  Ruleset ignored due to bad selector." },
+    { css: "x[a=5]{}", error: "Expected identifier or string for value in attribute selector but found ‘5’.  Ruleset ignored due to bad selector." },
+    { css: "x[$] {}", error: "Expected attribute name or namespace but found ‘$’.  Ruleset ignored due to bad selector." },
+    { css: "a[|5] {}", error: "Expected identifier for attribute name but found ‘5’.  Ruleset ignored due to bad selector." },
+    { css: "a[x|] {}", error: "Unknown namespace prefix ‘x’.  Ruleset ignored due to bad selector." },
+
+    { css: "x| {}", error: "Unknown namespace prefix ‘x’.  Ruleset ignored due to bad selector." },
+    { css: "a> {}", error: "Dangling combinator.  Ruleset ignored due to bad selector." },
+    { css: "~ {}", error: "Selector expected.  Ruleset ignored due to bad selector." },
+    { css: "| {}", error: "Expected element name or ‘*’ but found ‘ ’.  Ruleset ignored due to bad selector." },
+    { css: ". {}", error: "Expected identifier for class selector but found ‘ ’.  Ruleset ignored due to bad selector." },
+
+    { css: ":not() {}", error: "Missing argument in negation pseudo-class ‘)’.  Ruleset ignored due to bad selector." },
+  ];
+
+  var test = -1;
+  function nextTest() {
+    test++;
+    if (test == tests.length) {
+      SimpleTest.finish();
+      return;
+    }
+    let {css, error} = tests[test];
+    SimpleTest.expectConsoleMessages(function () { testbench.innerHTML = css },
+                                     [{ errorMessage: error }],
+                                     nextTest);
+  }
+
+  SimpleTest.waitForExplicitFinish();
+  nextTest();
+</script>
--- a/mobile/locales/l10n-changesets.json
+++ b/mobile/locales/l10n-changesets.json
--- a/python/mach/mach/config.py
+++ b/python/mach/mach/config.py
@ -19,14 +19,10 @@ from __future__ import absolute_import, unicode_literals
 import collections
 import os
 import sys
+import six
 from functools import wraps
-
-if sys.version_info[0] == 3:
-    from configparser import RawConfigParser, NoSectionError
-    str_type = str
-else:
-    from ConfigParser import RawConfigParser, NoSectionError
-    str_type = basestring
+from six.moves.configparser import RawConfigParser, NoSectionError
+from six import string_types as str_type


 class ConfigException(Exception):
@ -144,7 +140,7 @@ def reraise_attribute_error(func):
            return func(*args, **kwargs)
        except KeyError:
            exc_class, exc, tb = sys.exc_info()
-            raise AttributeError().__class__, exc, tb
+            six.reraise(AttributeError().__class__, exc, tb)
    return _


--- a/python/mach/setup.py
+++ b/python/mach/setup.py
@ -32,6 +32,7 @@ setup(
        'blessings',
        'mozfile',
        'mozprocess',
+        'six',
    ],
    tests_require=['mock'],
 )
--- a/python/mozboot/mozboot/archlinux.py
+++ b/python/mozboot/mozboot/archlinux.py
@ -75,7 +75,7 @@ class ArchlinuxBootstrapper(StyloInstall, BaseBootstrapper):
    ]

    def __init__(self, version, dist_id, **kwargs):
-        print 'Using an experimental bootstrapper for Archlinux.'
+        print('Using an experimental bootstrapper for Archlinux.')
        BaseBootstrapper.__init__(self, **kwargs)

    def install_system_packages(self):
--- a/python/mozboot/mozboot/windows.py
+++ b/python/mozboot/mozboot/windows.py
@ -45,7 +45,7 @@ class WindowsBootstrapper(BaseBootstrapper):
        if not self.which('pacman'):
            raise NotImplementedError('The Windows bootstrapper only works with msys2 with pacman. Get msys2 at '
                                      'http://msys2.github.io/')
-        print 'Using an experimental bootstrapper for Windows.'
+        print('Using an experimental bootstrapper for Windows.')

    def which(self, name):
        return BaseBootstrapper.which(self, name + '.exe')
--- a/python/mozbuild/mozbuild/action/exe_7z_archive.py
+++ b/python/mozbuild/mozbuild/action/exe_7z_archive.py
@ -23,7 +23,7 @@ def archive_exe(pkg_dir, tagfile, sfx_package, package):
        with open(package, 'wb') as o:
            for i in [mozpath.join(tmpdir, '7zSD.sfx'), tagfile, mozpath.join(tmpdir, 'app.7z')]:
                shutil.copyfileobj(open(i, 'rb'), o)
-        os.chmod(package, 0755)
+        os.chmod(package, 0o0755)
    finally:
        if pkg_dir:
            shutil.move('core', pkg_dir)
--- a/python/mozbuild/mozbuild/action/explode_aar.py
+++ b/python/mozbuild/mozbuild/action/explode_aar.py
@ -44,7 +44,7 @@ def explode(aar, destdir):
    assets = mozpath.join(destdir, 'assets')
    try:
        os.rmdir(assets)
-    except OSError, e:
+    except OSError as e:
        if e.errno in (errno.ENOTEMPTY, errno.ENOENT):
            pass
        else:
--- a/python/mozbuild/mozbuild/action/output_searchplugins_list.py
+++ b/python/mozbuild/mozbuild/action/output_searchplugins_list.py
@ -28,4 +28,4 @@ for region, overrides in searchinfo["regionOverrides"].iteritems():
      engines.add(replacement)

 # join() will take an iterable, not just a list.
-print '\n'.join(engines)
+print('\n'.join(engines))
--- a/python/mozbuild/mozbuild/action/tooltool.py
+++ b/python/mozbuild/mozbuild/action/tooltool.py
@ -372,9 +372,9 @@ def list_manifest(manifest_file):
        ))
        return False
    for f in manifest.file_records:
-        print "%s\t%s\t%s" % ("P" if f.present() else "-",
+        print("%s\t%s\t%s" % ("P" if f.present() else "-",
                              "V" if f.present() and f.validate() else "-",
-                              f.filename)
+                              f.filename))
    return True


@ -674,7 +674,7 @@ def fetch_files(manifest_file, base_urls, filenames=[], cache_folder=None,
                try:
                    if not os.path.exists(cache_folder):
                        log.info("Creating cache in %s..." % cache_folder)
-                        os.makedirs(cache_folder, 0700)
+                        os.makedirs(cache_folder, 0o0700)
                    shutil.copy(os.path.join(os.getcwd(), localfile.filename),
                                os.path.join(cache_folder, localfile.digest))
                    log.info("Local cache %s updated with %s" % (cache_folder,
--- a/python/mozbuild/mozbuild/configure/check_debug_ranges.py
+++ b/python/mozbuild/mozbuild/configure/check_debug_ranges.py
@ -59,4 +59,4 @@ def main(bin, compilation_unit):


 if __name__ == '__main__':
-    print main(*sys.argv[1:])
+    print(main(*sys.argv[1:]))
--- a/python/mozbuild/mozbuild/configure/libstdcxx.py
+++ b/python/mozbuild/mozbuild/configure/libstdcxx.py
@ -76,6 +76,6 @@ def find_version(e):

 if __name__ == '__main__':
    cxx_env = os.environ['CXX']
-    print 'MOZ_LIBSTDCXX_TARGET_VERSION=%s' % find_version(cxx_env)
+    print('MOZ_LIBSTDCXX_TARGET_VERSION=%s' % find_version(cxx_env))
    host_cxx_env = os.environ.get('HOST_CXX', cxx_env)
-    print 'MOZ_LIBSTDCXX_HOST_VERSION=%s' % find_version(host_cxx_env)
+    print('MOZ_LIBSTDCXX_HOST_VERSION=%s' % find_version(host_cxx_env))
--- a/python/mozbuild/mozbuild/configure/lint_util.py
+++ b/python/mozbuild/mozbuild/configure/lint_util.py
@ -30,7 +30,7 @@ def disassemble_as_iter(co):
            extended_arg = 0
            i += 2
            if op == dis.EXTENDED_ARG:
-                extended_arg = arg * 65536L
+                extended_arg = arg * 65536
                continue
            if op in dis.hasconst:
                yield opname, co.co_consts[arg]
--- a/python/mozbuild/mozbuild/doctor.py
+++ b/python/mozbuild/mozbuild/doctor.py
@ -212,7 +212,7 @@ class Doctor(object):
                        fsutil_output = subprocess.check_output(command)
                        status = 'GOOD, FIXED'
                        desc = 'lastaccess disabled systemwide'
-                    except subprocess.CalledProcessError, e:
+                    except subprocess.CalledProcessError as e:
                        desc = 'lastaccess enabled systemwide'
                        if e.output.find('denied') != -1:
                            status = 'BAD, FIX DENIED'
--- a/python/mozbuild/mozbuild/frontend/reader.py
+++ b/python/mozbuild/mozbuild/frontend/reader.py
@ -852,6 +852,18 @@ class BuildReader(object):
        self._execution_stack = []
        self._finder = finder

+        # Finder patterns to ignore when searching for moz.build files.
+        ignores = {
+            # Ignore fake moz.build files used for testing moz.build.
+            'python/mozbuild/mozbuild/test',
+
+            # Ignore object directories.
+            'obj*',
+        }
+
+        self._relevant_mozbuild_finder = FileFinder(self.config.topsrcdir,
+                                                    ignore=ignores)
+
        max_workers = cpu_count()
        self._gyp_worker_pool = ProcessPoolExecutor(max_workers=max_workers)
        self._gyp_processors = []
@ -904,20 +916,10 @@ class BuildReader(object):
        # In the future, we may traverse moz.build files by looking
        # for DIRS references in the AST, even if a directory is added behind
        # a conditional. For now, just walk the filesystem.
-        ignore = {
-            # Ignore fake moz.build files used for testing moz.build.
-            'python/mozbuild/mozbuild/test',
-
-            # Ignore object directories.
-            'obj*',
-        }
-
-        finder = FileFinder(self.config.topsrcdir, ignore=ignore)
-
        # The root doesn't get picked up by FileFinder.
        yield 'moz.build'

-        for path, f in finder.find('**/moz.build'):
+        for path, f in self._relevant_mozbuild_finder.find('**/moz.build'):
            yield path

    def find_sphinx_variables(self):
@ -1233,7 +1235,7 @@ class BuildReader(object):

        @memoize
        def exists(path):
-            return self._finder.get(path) is not None
+            return self._relevant_mozbuild_finder.get(path) is not None

        def itermozbuild(path):
            subpath = ''
@ -1249,8 +1251,7 @@ class BuildReader(object):
                    raise Exception('Path outside topsrcdir: %s' % path)
                path = mozpath.relpath(path, root)

-            result[path] = [p for p in itermozbuild(path)
-                              if exists(mozpath.join(root, p))]
+            result[path] = [p for p in itermozbuild(path) if exists(p)]

        return result

--- a/python/mozbuild/mozbuild/jar.py
+++ b/python/mozbuild/mozbuild/jar.py
@ -372,7 +372,7 @@ class JarMaker(object):
            jarfilepath = jarfile + '.jar'
            try:
                os.makedirs(os.path.dirname(jarfilepath))
-            except OSError, error:
+            except OSError as error:
                if error.errno != errno.EEXIST:
                    raise
            jf = ZipFile(jarfilepath, 'a', lock=True)
@ -514,7 +514,7 @@ class JarMaker(object):
            # remove previous link or file
            try:
                os.remove(out)
-            except OSError, e:
+            except OSError as e:
                if e.errno != errno.ENOENT:
                    raise
            return open(out, 'wb')
@ -525,7 +525,7 @@ class JarMaker(object):
            if not os.path.isdir(outdir):
                try:
                    os.makedirs(outdir)
-                except OSError, error:
+                except OSError as error:
                    if error.errno != errno.EEXIST:
                        raise
            return out
@ -541,7 +541,7 @@ class JarMaker(object):
            # remove previous link or file
            try:
                os.remove(out)
-            except OSError, e:
+            except OSError as e:
                if e.errno != errno.ENOENT:
                    raise
            if sys.platform != 'win32':
--- a/python/mozbuild/mozbuild/preprocessor.py
+++ b/python/mozbuild/mozbuild/preprocessor.py
@ -56,7 +56,7 @@ class Expression:
        self.__ignore_whitespace()
        self.e = self.__get_logical_or()
        if self.content:
-            raise Expression.ParseError, self
+            raise Expression.ParseError(self)

    def __get_logical_or(self):
        """
@ -157,7 +157,7 @@ class Expression:
                if word_len:
                    rv = Expression.__ASTLeaf('string', self.content[:word_len])
                else:
-                    raise Expression.ParseError, self
+                    raise Expression.ParseError(self)
        self.__strip(word_len)
        self.__ignore_whitespace()
        return rv
@ -196,7 +196,7 @@ class Expression:
                return left and right
            elif tok[1].value == '||':
                return left or right
-            raise Expression.ParseError, self
+            raise Expression.ParseError(self)

        # Mapping from token types to evaluator functions
        # Apart from (non-)equality, all these can be simple lambda forms.
--- a/python/mozbuild/mozbuild/test/test_util.py
+++ b/python/mozbuild/mozbuild/test/test_util.py
@ -110,7 +110,7 @@ class TestFileAvoidWrite(unittest.TestCase):
            '''
            def __call__(self, name, mode):
                if 'w' in mode:
-                    raise Exception, 'Unexpected open with write mode'
+                    raise Exception('Unexpected open with write mode')
                return MockedOpen.__call__(self, name, mode)

        with MyMockedOpen({'file': 'content'}):
--- a/python/mozbuild/mozbuild/util.py
+++ b/python/mozbuild/mozbuild/util.py
@ -152,7 +152,7 @@ def ensureParentDir(path):
    if d and not os.path.exists(path):
        try:
            os.makedirs(d)
-        except OSError, error:
+        except OSError as error:
            if error.errno != errno.EEXIST:
                raise

--- a/python/mozbuild/mozpack/archive.py
+++ b/python/mozbuild/mozpack/archive.py
@ -6,7 +6,6 @@ from __future__ import absolute_import

 import bz2
 import gzip
-import io
 import stat
 import tarfile

@ -37,7 +36,7 @@ def create_tar_from_files(fp, files):
                f = File(f)

            ti = tarfile.TarInfo(archive_path)
-            ti.mode = f.mode or 0644
+            ti.mode = f.mode or 0o0644
            ti.type = tarfile.REGTYPE

            if not ti.isreg():
--- a/python/mozbuild/mozpack/files.py
+++ b/python/mozbuild/mozpack/files.py
@ -145,13 +145,13 @@ class BaseFile(object):
        # - keep file type (e.g. S_IFREG)
        ret = stat.S_IFMT(mode)
        # - expand user read and execute permissions to everyone
-        if mode & 0400:
-            ret |= 0444
-        if mode & 0100:
-            ret |= 0111
-        # - keep user write permissions
-        if mode & 0200:
-            ret |= 0200
+        if mode & 0o0400:
+            ret |= 0o0444
+        if mode & 0o0100:
+            ret |= 0o0111
+         # - keep user write permissions
+        if mode & 0o0200:
+            ret |= 0o0200
        # - leave away sticky bit, setuid, setgid
        return ret

--- a/python/mozbuild/mozpack/mozjar.py
+++ b/python/mozbuild/mozpack/mozjar.py
@ -401,7 +401,7 @@ class JarReader(object):
            xattr = entry['external_attr']
            # Skip directories
            if (host == 0 and xattr & 0x10) or (host == 3 and
-                                                xattr & (040000 << 16)):
+                                                xattr & (0o040000 << 16)):
                continue
            entries[entry['filename']] = entry
            if entry['offset'] < preload:
@ -638,7 +638,7 @@ class JarWriter(object):
            # Set creator host system (upper byte of creator_version)
            # to 3 (Unix) so mode is honored when there is one.
            entry['creator_version'] |= 3 << 8
-            entry['external_attr'] = (mode & 0xFFFF) << 16L
+            entry['external_attr'] = (mode & 0xFFFF) << 16
        if deflater.compressed:
            entry['min_version'] = 20  # Version 2.0 supports deflated streams
            entry['general_flag'] = 2  # Max compression
--- a/python/mozlint/mozlint/roller.py
+++ b/python/mozlint/mozlint/roller.py
@ -9,8 +9,8 @@ import signal
 import sys
 import traceback
 from collections import defaultdict
-from multiprocessing import Manager, Pool, cpu_count
-from Queue import Empty
+from concurrent.futures import ProcessPoolExecutor
+from multiprocessing import cpu_count

 from .errors import LintersNotConfigured
 from .parser import Parser
@ -18,36 +18,25 @@ from .types import supported_types
 from .vcs import VCSHelper


-def _run_linters(queue, paths, **lintargs):
+def _run_linters(config, paths, **lintargs):
    results = defaultdict(list)
    failed = []

-    while True:
-        try:
-            # The astute reader may wonder what is preventing the worker from
-            # grabbing the next linter config from the queue after a SIGINT.
-            # Because this is a Manager.Queue(), it is itself in a child process
-            # which also received SIGINT. By the time the worker gets back here,
-            # the Queue is dead and IOError is raised.
-            config = queue.get(False)
-        except (Empty, IOError):
-            return results, failed
-
-        func = supported_types[config['type']]
-        res = func(paths, config, **lintargs) or []
-
-        if not isinstance(res, (list, tuple)):
-            if res:
-                failed.append(config['name'])
-            continue
+    func = supported_types[config['type']]
+    res = func(paths, config, **lintargs) or []

+    if not isinstance(res, (list, tuple)):
+        if res:
+            failed.append(config['name'])
+    else:
        for r in res:
            results[r.path].append(r)
+    return results, failed


-def _run_worker(*args, **lintargs):
+def _run_worker(*args, **kwargs):
    try:
-        return _run_linters(*args, **lintargs)
+        return _run_linters(*args, **kwargs)
    except Exception:
        # multiprocessing seems to munge worker exceptions, print
        # it here so it isn't lost.
@ -125,36 +114,23 @@ class LintRoller(object):
        # we're done adding to it.
        paths = map(os.path.abspath, paths)

-        # Set up multiprocessing
-        m = Manager()
-        queue = m.Queue()
-
-        for config in self.linters:
-            queue.put(config)
-
        num_procs = num_procs or cpu_count()
        num_procs = min(num_procs, len(self.linters))
-        pool = Pool(num_procs)

        all_results = defaultdict(list)
-        workers = []
-        for i in range(num_procs):
-            workers.append(
-                pool.apply_async(_run_worker, args=(queue, paths), kwds=self.lintargs))
-        pool.close()
-
-        # ignore SIGINT in parent so we can still get partial results
-        # from child processes. These should shutdown quickly anyway.
-        orig_sigint = signal.signal(signal.SIGINT, signal.SIG_IGN)
-        self.failed = []
-        for worker in workers:
-            # parent process blocks on worker.get()
-            results, failed = worker.get()
-            if failed:
-                self.failed.extend(failed)
-            for k, v in results.iteritems():
-                all_results[k].extend(v)
+        with ProcessPoolExecutor(num_procs) as executor:
+            futures = [executor.submit(_run_worker, config, paths, **self.lintargs)
+                       for config in self.linters]
+            # ignore SIGINT in parent so we can still get partial results
+            # from child processes. These should shutdown quickly anyway.
+            orig_sigint = signal.signal(signal.SIGINT, signal.SIG_IGN)
+            self.failed = []
+            for future in futures:
+                results, failed = future.result()
+                if failed:
+                    self.failed.extend(failed)
+                for k, v in results.iteritems():
+                    all_results[k].extend(v)

        signal.signal(signal.SIGINT, orig_sigint)
-        m.shutdown()
        return all_results
--- a/security/sandbox/mac/SandboxPolicies.h
+++ b/security/sandbox/mac/SandboxPolicies.h
@ -186,9 +186,13 @@ static const char contentSandboxRules[] = R"(
      (global-name "com.apple.audio.coreaudiod")
      (global-name "com.apple.audio.audiohald"))

-; bug 1376163
  (if (>= macosMinorVersion 13)
-    (allow mach-lookup (global-name "com.apple.audio.AudioComponentRegistrar")))
+    (allow mach-lookup
+      ; bug 1376163
+      (global-name "com.apple.audio.AudioComponentRegistrar")
+      ; bug 1392988
+      (xpc-service-name "com.apple.coremedia.videodecoder")
+      (xpc-service-name "com.apple.coremedia.videoencoder")))

 ; bug 1312273
  (if (= macosMinorVersion 9)
--- a/services/sync/locales/en-US/sync.properties
+++ b/services/sync/locales/en-US/sync.properties
@ -13,4 +13,4 @@ lastSync2.label = Last sync: %S
 signInToSync.description = Sign In To Sync

 syncnow.label = Sync Now
-syncing2.label = Syncing…
+syncingtabs.label = Syncing Tabs…
--- a/servo/components/config/opts.rs
+++ b/servo/components/config/opts.rs
@ -516,9 +516,9 @@ pub fn default_opts() -> Opts {
        bubble_inline_sizes_separately: false,
        show_debug_fragment_borders: false,
        show_debug_parallel_layout: false,
-        enable_text_antialiasing: false,
-        enable_subpixel_text_antialiasing: false,
-        enable_canvas_antialiasing: false,
+        enable_text_antialiasing: true,
+        enable_subpixel_text_antialiasing: true,
+        enable_canvas_antialiasing: true,
        trace_layout: false,
        debugger_port: None,
        devtools_port: None,
--- a/servo/components/selectors/builder.rs
+++ b/servo/components/selectors/builder.rs
@ -90,6 +90,12 @@ impl<Impl: SelectorImpl> SelectorBuilder<Impl> {
        self.simple_selectors.is_empty()
    }

+    /// Returns true if combinators have ever been pushed to this builder.
+    #[inline(always)]
+    pub fn has_combinators(&self) -> bool {
+        !self.combinators.is_empty()
+    }
+
    /// Consumes the builder, producing a Selector.
    #[inline(always)]
    pub fn build(&mut self, parsed_pseudo: bool) -> ThinArc<SpecificityAndFlags, Component<Impl>> {
--- a/servo/components/selectors/parser.rs
+++ b/servo/components/selectors/parser.rs
@ -49,18 +49,23 @@ fn to_ascii_lowercase(s: &str) -> Cow<str> {
 #[derive(Clone, Debug, PartialEq)]
 pub enum SelectorParseError<'i, T> {
    PseudoElementInComplexSelector,
-    NoQualifiedNameInAttributeSelector,
-    TooManyCompoundSelectorComponentsInNegation,
-    NegationSelectorComponentNotNamespace,
-    NegationSelectorComponentNotLocalName,
+    NoQualifiedNameInAttributeSelector(Token<'i>),
    EmptySelector,
+    DanglingCombinator,
    NonSimpleSelectorInNegation,
-    UnexpectedTokenInAttributeSelector,
-    PseudoElementExpectedColon,
-    PseudoElementExpectedIdent,
-    UnsupportedPseudoClass,
+    UnexpectedTokenInAttributeSelector(Token<'i>),
+    PseudoElementExpectedColon(Token<'i>),
+    PseudoElementExpectedIdent(Token<'i>),
+    NoIdentForPseudo(Token<'i>),
+    UnsupportedPseudoClassOrElement(CowRcStr<'i>),
    UnexpectedIdent(CowRcStr<'i>),
    ExpectedNamespace(CowRcStr<'i>),
+    ExpectedBarInAttr(Token<'i>),
+    BadValueInAttr(Token<'i>),
+    InvalidQualNameInAttr(Token<'i>),
+    ExplicitNamespaceUnexpectedToken(Token<'i>),
+    ClassNeedsIdent(Token<'i>),
+    EmptyNegation,
    Custom(T),
 }

@ -136,7 +141,7 @@ pub trait Parser<'i> {
    fn parse_non_ts_pseudo_class(&self, name: CowRcStr<'i>)
                                 -> Result<<Self::Impl as SelectorImpl>::NonTSPseudoClass,
                                           ParseError<'i, SelectorParseError<'i, Self::Error>>> {
-        Err(ParseError::Custom(SelectorParseError::UnexpectedIdent(name)))
+        Err(ParseError::Custom(SelectorParseError::UnsupportedPseudoClassOrElement(name)))
    }

    fn parse_non_ts_functional_pseudo_class<'t>
@ -144,20 +149,20 @@ pub trait Parser<'i> {
         -> Result<<Self::Impl as SelectorImpl>::NonTSPseudoClass,
                   ParseError<'i, SelectorParseError<'i, Self::Error>>>
    {
-        Err(ParseError::Custom(SelectorParseError::UnexpectedIdent(name)))
+        Err(ParseError::Custom(SelectorParseError::UnsupportedPseudoClassOrElement(name)))
    }

    fn parse_pseudo_element(&self, name: CowRcStr<'i>)
                            -> Result<<Self::Impl as SelectorImpl>::PseudoElement,
                                      ParseError<'i, SelectorParseError<'i, Self::Error>>> {
-        Err(ParseError::Custom(SelectorParseError::UnexpectedIdent(name)))
+        Err(ParseError::Custom(SelectorParseError::UnsupportedPseudoClassOrElement(name)))
    }

    fn parse_functional_pseudo_element<'t>
        (&self, name: CowRcStr<'i>, _arguments: &mut CssParser<'i, 't>)
         -> Result<<Self::Impl as SelectorImpl>::PseudoElement,
                   ParseError<'i, SelectorParseError<'i, Self::Error>>> {
-        Err(ParseError::Custom(SelectorParseError::UnexpectedIdent(name)))
+        Err(ParseError::Custom(SelectorParseError::UnsupportedPseudoClassOrElement(name)))
    }

    fn default_namespace(&self) -> Option<<Self::Impl as SelectorImpl>::NamespaceUrl> {
@ -1041,7 +1046,12 @@ fn parse_selector<'i, 't, P, E, Impl>(
    let mut parsed_pseudo_element;
    'outer_loop: loop {
        // Parse a sequence of simple selectors.
-        parsed_pseudo_element = parse_compound_selector(parser, input, &mut builder)?;
+        parsed_pseudo_element = match parse_compound_selector(parser, input, &mut builder) {
+            Ok(result) => result,
+            Err(ParseError::Custom(SelectorParseError::EmptySelector)) if builder.has_combinators() =>
+                return Err(SelectorParseError::DanglingCombinator.into()),
+            Err(e) => return Err(e),
+        };
        if parsed_pseudo_element {
            break;
        }
@ -1106,9 +1116,10 @@ fn parse_type_selector<'i, 't, P, E, Impl, S>(parser: &P, input: &mut CssParser<
          Impl: SelectorImpl,
          S: Push<Component<Impl>>,
 {
-    match parse_qualified_name(parser, input, /* in_attr_selector = */ false)? {
-        None => Ok(false),
-        Some((namespace, local_name)) => {
+    match parse_qualified_name(parser, input, /* in_attr_selector = */ false) {
+        Err(ParseError::Basic(BasicParseError::EndOfInput)) |
+        Ok(OptionalQName::None(_)) => Ok(false),
+        Ok(OptionalQName::Some(namespace, local_name)) => {
            match namespace {
                QNamePrefix::ImplicitAnyNamespace => {}
                QNamePrefix::ImplicitDefaultNamespace(url) => {
@ -1157,6 +1168,7 @@ fn parse_type_selector<'i, 't, P, E, Impl, S>(parser: &P, input: &mut CssParser<
            }
            Ok(true)
        }
+        Err(e) => Err(e)
    }
 }

@ -1176,13 +1188,19 @@ enum QNamePrefix<Impl: SelectorImpl> {
    ExplicitNamespace(Impl::NamespacePrefix, Impl::NamespaceUrl),  // `prefix|foo`
 }

+enum OptionalQName<'i, Impl: SelectorImpl> {
+    Some(QNamePrefix<Impl>, Option<CowRcStr<'i>>),
+    None(Token<'i>),
+}
+
 /// * `Err(())`: Invalid selector, abort
-/// * `Ok(None)`: Not a simple selector, could be something else. `input` was not consumed.
-/// * `Ok(Some((namespace, local_name)))`: `None` for the local name means a `*` universal selector
+/// * `Ok(None(token))`: Not a simple selector, could be something else. `input` was not consumed,
+///                      but the token is still returned.
+/// * `Ok(Some(namespace, local_name))`: `None` for the local name means a `*` universal selector
 fn parse_qualified_name<'i, 't, P, E, Impl>
                       (parser: &P, input: &mut CssParser<'i, 't>,
                        in_attr_selector: bool)
-                        -> Result<Option<(QNamePrefix<Impl>, Option<CowRcStr<'i>>)>,
+                        -> Result<OptionalQName<'i, Impl>,
                                  ParseError<'i, SelectorParseError<'i, E>>>
    where P: Parser<'i, Impl=Impl, Error=E>, Impl: SelectorImpl
 {
@ -1191,18 +1209,19 @@ fn parse_qualified_name<'i, 't, P, E, Impl>
            Some(url) => QNamePrefix::ImplicitDefaultNamespace(url),
            None => QNamePrefix::ImplicitAnyNamespace,
        };
-        Ok(Some((namespace, local_name)))
+        Ok(OptionalQName::Some(namespace, local_name))
    };

    let explicit_namespace = |input: &mut CssParser<'i, 't>, namespace| {
        match input.next_including_whitespace() {
            Ok(&Token::Delim('*')) if !in_attr_selector => {
-                Ok(Some((namespace, None)))
+                Ok(OptionalQName::Some(namespace, None))
            },
            Ok(&Token::Ident(ref local_name)) => {
-                Ok(Some((namespace, Some(local_name.clone()))))
+                Ok(OptionalQName::Some(namespace, Some(local_name.clone())))
            },
-            Ok(t) => Err(ParseError::Basic(BasicParseError::UnexpectedToken(t.clone()))),
+            Ok(t) if in_attr_selector => Err(SelectorParseError::InvalidQualNameInAttr(t.clone()).into()),
+            Ok(t) => Err(SelectorParseError::ExplicitNamespaceUnexpectedToken(t.clone()).into()),
            Err(e) => Err(ParseError::Basic(e)),
        }
    };
@ -1223,7 +1242,7 @@ fn parse_qualified_name<'i, 't, P, E, Impl>
                _ => {
                    input.reset(&after_ident);
                    if in_attr_selector {
-                        Ok(Some((QNamePrefix::ImplicitNoNamespace, Some(value))))
+                        Ok(OptionalQName::Some(QNamePrefix::ImplicitNoNamespace, Some(value)))
                    } else {
                        default_namespace(Some(value))
                    }
@ -1241,7 +1260,7 @@ fn parse_qualified_name<'i, 't, P, E, Impl>
                    input.reset(&after_star);
                    if in_attr_selector {
                        match result {
-                            Ok(t) => Err(ParseError::Basic(BasicParseError::UnexpectedToken(t))),
+                            Ok(t) => Err(SelectorParseError::ExpectedBarInAttr(t).into()),
                            Err(e) => Err(ParseError::Basic(e)),
                        }
                    } else {
@ -1253,9 +1272,13 @@ fn parse_qualified_name<'i, 't, P, E, Impl>
        Ok(Token::Delim('|')) => {
            explicit_namespace(input, QNamePrefix::ExplicitNoNamespace)
        }
-        _ => {
+        Ok(t) => {
            input.reset(&start);
-            Ok(None)
+            Ok(OptionalQName::None(t))
+        }
+        Err(e) => {
+            input.reset(&start);
+            Err(e.into())
        }
    }
 }
@ -1269,9 +1292,10 @@ fn parse_attribute_selector<'i, 't, P, E, Impl>(parser: &P, input: &mut CssParse
    let namespace;
    let local_name;
    match parse_qualified_name(parser, input, /* in_attr_selector = */ true)? {
-        None => return Err(ParseError::Custom(SelectorParseError::NoQualifiedNameInAttributeSelector)),
-        Some((_, None)) => unreachable!(),
-        Some((ns, Some(ln))) => {
+        OptionalQName::None(t) =>
+            return Err(ParseError::Custom(SelectorParseError::NoQualifiedNameInAttributeSelector(t))),
+        OptionalQName::Some(_, None) => unreachable!(),
+        OptionalQName::Some(ns, Some(ln)) => {
            local_name = ln;
            namespace = match ns {
                QNamePrefix::ImplicitNoNamespace |
@ -1292,10 +1316,7 @@ fn parse_attribute_selector<'i, 't, P, E, Impl>(parser: &P, input: &mut CssParse
        }
    }

-    let operator;
-    let value;
-    let never_matches;
-    match input.next() {
+    let operator = match input.next() {
        // [foo]
        Err(_) => {
            let local_name_lower = to_ascii_lowercase(&local_name).as_ref().into();
@ -1317,43 +1338,38 @@ fn parse_attribute_selector<'i, 't, P, E, Impl>(parser: &P, input: &mut CssParse
        }

        // [foo=bar]
-        Ok(&Token::Delim('=')) => {
-            value = input.expect_ident_or_string()?.clone();
-            never_matches = false;
-            operator = AttrSelectorOperator::Equal;
-        }
+        Ok(&Token::Delim('=')) => AttrSelectorOperator::Equal,
        // [foo~=bar]
-        Ok(&Token::IncludeMatch) => {
-            value = input.expect_ident_or_string()?.clone();
-            never_matches = value.is_empty() || value.contains(SELECTOR_WHITESPACE);
-            operator = AttrSelectorOperator::Includes;
-        }
+        Ok(&Token::IncludeMatch) => AttrSelectorOperator::Includes,
        // [foo|=bar]
-        Ok(&Token::DashMatch) => {
-            value = input.expect_ident_or_string()?.clone();
-            never_matches = false;
-            operator = AttrSelectorOperator::DashMatch;
-        }
+        Ok(&Token::DashMatch) => AttrSelectorOperator::DashMatch,
        // [foo^=bar]
-        Ok(&Token::PrefixMatch) => {
-            value = input.expect_ident_or_string()?.clone();
-            never_matches = value.is_empty();
-            operator = AttrSelectorOperator::Prefix;
-        }
+        Ok(&Token::PrefixMatch) => AttrSelectorOperator::Prefix,
        // [foo*=bar]
-        Ok(&Token::SubstringMatch) => {
-            value = input.expect_ident_or_string()?.clone();
-            never_matches = value.is_empty();
-            operator = AttrSelectorOperator::Substring;
-        }
+        Ok(&Token::SubstringMatch) => AttrSelectorOperator::Substring,
        // [foo$=bar]
-        Ok(&Token::SuffixMatch) => {
-            value = input.expect_ident_or_string()?.clone();
-            never_matches = value.is_empty();
-            operator = AttrSelectorOperator::Suffix;
+        Ok(&Token::SuffixMatch) => AttrSelectorOperator::Suffix,
+        Ok(t) => return Err(SelectorParseError::UnexpectedTokenInAttributeSelector(t.clone()).into())
+    };
+
+    let value = match input.expect_ident_or_string() {
+        Ok(t) => t.clone(),
+        Err(BasicParseError::UnexpectedToken(t)) =>
+            return Err(SelectorParseError::BadValueInAttr(t.clone()).into()),
+        Err(e) => return Err(e.into()),
+    };
+    let never_matches = match operator {
+        AttrSelectorOperator::Equal |
+        AttrSelectorOperator::DashMatch => false,
+
+        AttrSelectorOperator::Includes => {
+            value.is_empty() || value.contains(SELECTOR_WHITESPACE)
        }
-        _ => return Err(SelectorParseError::UnexpectedTokenInAttributeSelector.into())
-    }
+
+        AttrSelectorOperator::Prefix |
+        AttrSelectorOperator::Substring |
+        AttrSelectorOperator::Suffix => value.is_empty()
+    };

    let mut case_sensitivity = parse_attribute_flags(input)?;

@ -1429,13 +1445,19 @@ fn parse_negation<'i, 't, P, E, Impl>(parser: &P,

    // Get exactly one simple selector. The parse logic in the caller will verify
    // that there are no trailing tokens after we're done.
-    if !parse_type_selector(parser, input, &mut sequence)? {
+    let is_type_sel = match parse_type_selector(parser, input, &mut sequence) {
+        Ok(result) => result,
+        Err(ParseError::Basic(BasicParseError::EndOfInput)) =>
+            return Err(SelectorParseError::EmptyNegation.into()),
+        Err(e) => return Err(e.into()),
+    };
+    if !is_type_sel {
        match parse_one_simple_selector(parser, input, /* inside_negation = */ true)? {
            Some(SimpleSelectorParseResult::SimpleSelector(s)) => {
                sequence.push(s);
            },
            None => {
-                return Err(ParseError::Custom(SelectorParseError::EmptySelector));
+                return Err(ParseError::Custom(SelectorParseError::EmptyNegation));
            },
            Some(SimpleSelectorParseResult::PseudoElement(_)) => {
                return Err(ParseError::Custom(SelectorParseError::NonSimpleSelectorInNegation));
@ -1492,20 +1514,21 @@ fn parse_compound_selector<'i, 't, P, E, Impl>(
                    match input.next_including_whitespace() {
                        Ok(&Token::Colon) => {},
                        Ok(&Token::WhiteSpace(_)) | Err(_) => break,
-                        _ => return Err(SelectorParseError::PseudoElementExpectedColon.into()),
+                        Ok(t) =>
+                            return Err(SelectorParseError::PseudoElementExpectedColon(t.clone()).into()),
                    }

                    // TODO(emilio): Functional pseudo-classes too?
                    // We don't need it for now.
-                    let name = match input.next_including_whitespace() {
-                        Ok(&Token::Ident(ref name)) => name.clone(),
-                        _ => return Err(SelectorParseError::PseudoElementExpectedIdent.into()),
+                    let name = match input.next_including_whitespace()? {
+                        &Token::Ident(ref name) => name.clone(),
+                        t => return Err(SelectorParseError::NoIdentForPseudo(t.clone()).into()),
                    };

                    let pseudo_class =
-                        P::parse_non_ts_pseudo_class(parser, name)?;
+                        P::parse_non_ts_pseudo_class(parser, name.clone())?;
                    if !p.supports_pseudo_class(&pseudo_class) {
-                        return Err(SelectorParseError::UnsupportedPseudoClass.into());
+                        return Err(SelectorParseError::UnsupportedPseudoClassOrElement(name).into());
                    }
                    state_selectors.push(Component::NonTSPseudoClass(pseudo_class));
                }
@ -1604,7 +1627,7 @@ fn parse_one_simple_selector<'i, 't, P, E, Impl>(parser: &P,
                    let class = Component::Class(class.as_ref().into());
                    Ok(Some(SimpleSelectorParseResult::SimpleSelector(class)))
                }
-                ref t => Err(ParseError::Basic(BasicParseError::UnexpectedToken(t.clone()))),
+                ref t => Err(SelectorParseError::ClassNeedsIdent(t.clone()).into()),
            }
        }
        Ok(Token::SquareBracketBlock) => {
@ -1619,7 +1642,7 @@ fn parse_one_simple_selector<'i, 't, P, E, Impl>(parser: &P,
            let (name, is_functional) = match next_token {
                Token::Ident(name) => (name, false),
                Token::Function(name) => (name, true),
-                t => return Err(ParseError::Basic(BasicParseError::UnexpectedToken(t))),
+                t => return Err(SelectorParseError::PseudoElementExpectedIdent(t).into()),
            };
            let is_pseudo_element = !is_single_colon ||
                P::is_pseudo_element_allows_single_colon(&name);
--- a/servo/components/style/gecko/selector_parser.rs
+++ b/servo/components/style/gecko/selector_parser.rs
@ -308,7 +308,7 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
             keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
                match_ignore_ascii_case! { &name,
                    $($css => NonTSPseudoClass::$name,)*
-                    _ => return Err(::selectors::parser::SelectorParseError::UnexpectedIdent(
+                    _ => return Err(::selectors::parser::SelectorParseError::UnsupportedPseudoClassOrElement(
                        name.clone()).into())
                }
            }
@ -317,7 +317,7 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
        if self.is_pseudo_class_enabled(&pseudo_class) {
            Ok(pseudo_class)
        } else {
-            Err(SelectorParseError::UnexpectedIdent(name).into())
+            Err(SelectorParseError::UnsupportedPseudoClassOrElement(name).into())
        }
    }

@ -354,7 +354,7 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
                        }
                        NonTSPseudoClass::MozAny(selectors.into_boxed_slice())
                    }
-                    _ => return Err(SelectorParseError::UnexpectedIdent(name.clone()).into())
+                    _ => return Err(SelectorParseError::UnsupportedPseudoClassOrElement(name.clone()).into())
                }
            }
        }
@ -362,13 +362,13 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
        if self.is_pseudo_class_enabled(&pseudo_class) {
            Ok(pseudo_class)
        } else {
-            Err(SelectorParseError::UnexpectedIdent(name).into())
+            Err(SelectorParseError::UnsupportedPseudoClassOrElement(name).into())
        }
    }

    fn parse_pseudo_element(&self, name: CowRcStr<'i>) -> Result<PseudoElement, ParseError<'i>> {
        PseudoElement::from_slice(&name, self.in_user_agent_stylesheet())
-            .ok_or(SelectorParseError::UnexpectedIdent(name.clone()).into())
+            .ok_or(SelectorParseError::UnsupportedPseudoClassOrElement(name.clone()).into())
    }

    fn parse_functional_pseudo_element<'t>(&self, name: CowRcStr<'i>,
@ -392,7 +392,7 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
                return Ok(pseudo);
            }
        }
-        Err(SelectorParseError::UnexpectedIdent(name.clone()).into())
+        Err(SelectorParseError::UnsupportedPseudoClassOrElement(name.clone()).into())
    }

    fn default_namespace(&self) -> Option<Namespace> {
--- a/servo/components/style/stylist.rs
+++ b/servo/components/style/stylist.rs
@ -257,7 +257,7 @@ impl DocumentCascadeData {
                            Some(pseudo) => {
                                origin_cascade_data
                                    .pseudos_map
-                                    .get_or_insert_with(&pseudo.canonical(), SelectorMap::new)
+                                    .get_or_insert_with(&pseudo.canonical(), || Box::new(SelectorMap::new()))
                                    .expect("Unexpected tree pseudo-element?")
                            }
                        };
@ -1797,7 +1797,11 @@ struct CascadeData {

    /// Rules from stylesheets at this `CascadeData`'s origin that correspond
    /// to a given pseudo-element.
-    pseudos_map: PerPseudoElementMap<SelectorMap<Rule>>,
+    ///
+    /// FIXME(emilio): There are a bunch of wasted entries here in practice.
+    /// Figure out a good way to do a `PerNonAnonBox` and `PerAnonBox` (for
+    /// `precomputed_values_for_pseudo`) without duplicating a lot of code.
+    pseudos_map: PerPseudoElementMap<Box<SelectorMap<Rule>>>,

    /// A map with all the animations at this `CascadeData`'s origin, indexed
    /// by name.
@ -1875,7 +1879,7 @@ impl CascadeData {
    #[inline]
    fn borrow_for_pseudo(&self, pseudo: Option<&PseudoElement>) -> Option<&SelectorMap<Rule>> {
        match pseudo {
-            Some(pseudo) => self.pseudos_map.get(&pseudo.canonical()),
+            Some(pseudo) => self.pseudos_map.get(&pseudo.canonical()).map(|p| &**p),
            None => Some(&self.element_map),
        }
    }
--- a/servo/ports/geckolib/error_reporter.rs
+++ b/servo/ports/geckolib/error_reporter.rs
@ -161,7 +161,7 @@ fn token_to_str<'a>(t: Token<'a>) -> String {
            format!("{}{}", i, escape_css_ident(&*unit)),
        Token::Dimension { value, ref unit, .. } =>
            format!("{}{}", value, escape_css_ident(&*unit)),
-        Token::WhiteSpace(_) => "whitespace".into(),
+        Token::WhiteSpace(s) => s.into(),
        Token::Comment(_) => "comment".into(),
        Token::Colon => ":".into(),
        Token::Semicolon => ";".into(),
@ -194,7 +194,7 @@ enum Action {

 trait ErrorHelpers<'a> {
    fn error_data(self) -> (CowRcStr<'a>, ParseError<'a>);
-    fn error_params(self) -> (ErrorString<'a>, Option<ErrorString<'a>>);
+    fn error_params(self) -> ErrorParams<'a>;
    fn to_gecko_message(&self) -> (Option<&'static [u8]>, &'static [u8], Action);
 }

@ -203,7 +203,9 @@ fn extract_error_param<'a>(err: ParseError<'a>) -> Option<ErrorString<'a>> {
        CssParseError::Basic(BasicParseError::UnexpectedToken(t)) =>
            ErrorString::UnexpectedToken(t),

-        CssParseError::Basic(BasicParseError::AtRuleInvalid(i)) =>
+        CssParseError::Basic(BasicParseError::AtRuleInvalid(i)) |
+        CssParseError::Custom(SelectorParseError::Custom(
+            StyleParseError::UnsupportedAtRule(i))) =>
            ErrorString::Snippet(format!("@{}", escape_css_ident(&i)).into()),

        CssParseError::Custom(SelectorParseError::Custom(
@ -214,9 +216,6 @@ fn extract_error_param<'a>(err: ParseError<'a>) -> Option<ErrorString<'a>> {
        CssParseError::Custom(SelectorParseError::UnexpectedIdent(ident)) =>
            ErrorString::Ident(ident),

-        CssParseError::Custom(SelectorParseError::ExpectedNamespace(namespace)) =>
-            ErrorString::Ident(namespace),
-
        CssParseError::Custom(SelectorParseError::Custom(
            StyleParseError::PropertyDeclaration(
                PropertyDeclarationParseError::UnknownProperty(property)))) =>
@ -236,17 +235,54 @@ fn extract_value_error_param<'a>(err: ValueParseError<'a>) -> ErrorString<'a> {
    }
 }

+struct ErrorParams<'a> {
+    prefix_param: Option<ErrorString<'a>>,
+    main_param: Option<ErrorString<'a>>,
+}
+
 /// If an error parameter is present in the given error, return it. Additionally return
 /// a second parameter if it exists, for use in the prefix for the eventual error message.
-fn extract_error_params<'a>(err: ParseError<'a>) -> Option<(ErrorString<'a>, Option<ErrorString<'a>>)> {
-    match err {
+fn extract_error_params<'a>(err: ParseError<'a>) -> Option<ErrorParams<'a>> {
+    let (main, prefix) = match err {
        CssParseError::Custom(SelectorParseError::Custom(
            StyleParseError::PropertyDeclaration(
                PropertyDeclarationParseError::InvalidValue(property, Some(e))))) =>
-            Some((ErrorString::Snippet(property.into()), Some(extract_value_error_param(e)))),
+            (Some(ErrorString::Snippet(property.into())), Some(extract_value_error_param(e))),

-        err => extract_error_param(err).map(|e| (e, None)),
-    }
+        CssParseError::Custom(SelectorParseError::UnexpectedTokenInAttributeSelector(t)) |
+        CssParseError::Custom(SelectorParseError::BadValueInAttr(t)) |
+        CssParseError::Custom(SelectorParseError::ExpectedBarInAttr(t)) |
+        CssParseError::Custom(SelectorParseError::NoQualifiedNameInAttributeSelector(t)) |
+        CssParseError::Custom(SelectorParseError::InvalidQualNameInAttr(t)) |
+        CssParseError::Custom(SelectorParseError::ExplicitNamespaceUnexpectedToken(t)) |
+        CssParseError::Custom(SelectorParseError::PseudoElementExpectedIdent(t)) |
+        CssParseError::Custom(SelectorParseError::NoIdentForPseudo(t)) |
+        CssParseError::Custom(SelectorParseError::ClassNeedsIdent(t)) |
+        CssParseError::Custom(SelectorParseError::PseudoElementExpectedColon(t)) =>
+            (None, Some(ErrorString::UnexpectedToken(t))),
+
+        CssParseError::Custom(SelectorParseError::ExpectedNamespace(namespace)) =>
+            (None, Some(ErrorString::Ident(namespace))),
+
+        CssParseError::Custom(SelectorParseError::UnsupportedPseudoClassOrElement(p)) =>
+            (None, Some(ErrorString::Ident(p))),
+
+        CssParseError::Custom(SelectorParseError::EmptySelector) |
+        CssParseError::Custom(SelectorParseError::DanglingCombinator) =>
+            (None, None),
+
+        CssParseError::Custom(SelectorParseError::EmptyNegation) =>
+            (None, Some(ErrorString::Snippet(")".into()))),
+
+        err => match extract_error_param(err) {
+            Some(e) => (Some(e), None),
+            None => return None,
+        }
+    };
+    Some(ErrorParams {
+        main_param: main,
+        prefix_param: prefix,
+    })
 }

 impl<'a> ErrorHelpers<'a> for ContextualParseError<'a> {
@ -273,9 +309,12 @@ impl<'a> ErrorHelpers<'a> for ContextualParseError<'a> {
        }
    }

-    fn error_params(self) -> (ErrorString<'a>, Option<ErrorString<'a>>) {
+    fn error_params(self) -> ErrorParams<'a> {
        let (s, error) = self.error_data();
-        extract_error_params(error).unwrap_or((ErrorString::Snippet(s), None))
+        extract_error_params(error).unwrap_or_else(|| ErrorParams {
+            main_param: Some(ErrorString::Snippet(s)),
+            prefix_param: None
+        })
    }

    fn to_gecko_message(&self) -> (Option<&'static [u8]>, &'static [u8], Action) {
@ -303,15 +342,52 @@ impl<'a> ErrorHelpers<'a> for ContextualParseError<'a> {
                (b"PEKeyframeBadName\0", Action::Nothing),
            ContextualParseError::UnsupportedKeyframePropertyDeclaration(..) =>
                (b"PEBadSelectorKeyframeRuleIgnored\0", Action::Nothing),
-            ContextualParseError::InvalidRule(
-                _, CssParseError::Custom(SelectorParseError::ExpectedNamespace(_))) =>
-                (b"PEUnknownNamespacePrefix\0", Action::Nothing),
            ContextualParseError::InvalidRule(
                _, CssParseError::Custom(SelectorParseError::Custom(
                StyleParseError::UnexpectedTokenWithinNamespace(_)))) =>
                (b"PEAtNSUnexpected\0", Action::Nothing),
-            ContextualParseError::InvalidRule(..) =>
-                (b"PEBadSelectorRSIgnored\0", Action::Nothing),
+            ContextualParseError::InvalidRule(
+                _, CssParseError::Basic(BasicParseError::AtRuleInvalid(_))) |
+            ContextualParseError::InvalidRule(
+                _, CssParseError::Custom(SelectorParseError::Custom(
+                    StyleParseError::UnsupportedAtRule(_)))) =>
+                (b"PEUnknownAtRule\0", Action::Nothing),
+            ContextualParseError::InvalidRule(_, ref err) => {
+                let prefix = match *err {
+                    CssParseError::Custom(SelectorParseError::UnexpectedTokenInAttributeSelector(_)) =>
+                        Some(&b"PEAttSelUnexpected\0"[..]),
+                    CssParseError::Custom(SelectorParseError::ExpectedBarInAttr(_)) =>
+                        Some(&b"PEAttSelNoBar\0"[..]),
+                    CssParseError::Custom(SelectorParseError::BadValueInAttr(_)) =>
+                        Some(&b"PEAttSelBadValue\0"[..]),
+                    CssParseError::Custom(SelectorParseError::NoQualifiedNameInAttributeSelector(_)) =>
+                        Some(&b"PEAttributeNameOrNamespaceExpected\0"[..]),
+                    CssParseError::Custom(SelectorParseError::InvalidQualNameInAttr(_)) =>
+                        Some(&b"PEAttributeNameExpected\0"[..]),
+                    CssParseError::Custom(SelectorParseError::ExplicitNamespaceUnexpectedToken(_)) =>
+                        Some(&b"PETypeSelNotType\0"[..]),
+                    CssParseError::Custom(SelectorParseError::ExpectedNamespace(_)) =>
+                       Some(&b"PEUnknownNamespacePrefix\0"[..]),
+                    CssParseError::Custom(SelectorParseError::EmptySelector) =>
+                        Some(&b"PESelectorGroupNoSelector\0"[..]),
+                    CssParseError::Custom(SelectorParseError::DanglingCombinator) =>
+                        Some(&b"PESelectorGroupExtraCombinator\0"[..]),
+                    CssParseError::Custom(SelectorParseError::UnsupportedPseudoClassOrElement(_)) =>
+                        Some(&b"PEPseudoSelUnknown\0"[..]),
+                    CssParseError::Custom(SelectorParseError::PseudoElementExpectedColon(_)) =>
+                        Some(&b"PEPseudoSelEndOrUserActionPC\0"[..]),
+                    CssParseError::Custom(SelectorParseError::NoIdentForPseudo(_)) =>
+                        Some(&b"PEPseudoClassArgNotIdent\0"[..]),
+                    CssParseError::Custom(SelectorParseError::PseudoElementExpectedIdent(_)) =>
+                        Some(&b"PEPseudoSelBadName\0"[..]),
+                    CssParseError::Custom(SelectorParseError::ClassNeedsIdent(_)) =>
+                        Some(&b"PEClassSelNotIdent\0"[..]),
+                    CssParseError::Custom(SelectorParseError::EmptyNegation) =>
+                        Some(&b"PENegationBadArg\0"[..]),
+                    _ => None,
+                };
+                return (prefix, b"PEBadSelectorRSIgnored\0", Action::Nothing);
+            }
            ContextualParseError::UnsupportedRule(..) =>
                (b"PEDeclDropped\0", Action::Nothing),
            ContextualParseError::UnsupportedViewportDescriptorDeclaration(..) |
@ -340,17 +416,20 @@ impl ParseErrorReporter for ErrorReporter {
            Action::Skip => b"PEDeclSkipped\0".as_ptr(),
            Action::Drop => b"PEDeclDropped\0".as_ptr(),
        };
-        let (param, pre_param) = error.error_params();
-        let param = param.into_str();
+        let params = error.error_params();
+        let param = params.main_param;
+        let pre_param = params.prefix_param;
+        let param = param.map(|p| p.into_str());
        let pre_param = pre_param.map(|p| p.into_str());
+        let param_ptr = param.as_ref().map_or(ptr::null(), |p| p.as_ptr());
        let pre_param_ptr = pre_param.as_ref().map_or(ptr::null(), |p| p.as_ptr());
        // The CSS source text is unused and will be removed in bug 1381188.
        let source = "";
        unsafe {
            Gecko_ReportUnexpectedCSSError(self.0,
                                           name.as_ptr() as *const _,
-                                           param.as_ptr() as *const _,
-                                           param.len() as u32,
+                                           param_ptr as *const _,
+                                           param.as_ref().map_or(0, |p| p.len()) as u32,
                                           pre.map_or(ptr::null(), |p| p.as_ptr()) as *const _,
                                           pre_param_ptr as *const _,
                                           pre_param.as_ref().map_or(0, |p| p.len()) as u32,
--- a/taskcluster/ci/source-test/python-tests.yml
+++ b/taskcluster/ci/source-test/python-tests.yml
@ -148,3 +148,23 @@ mozlint:
        files-changed:
            - 'python/mozlint/**'
            - 'python/mach_commands.py'
+
+python3:
+    description: regression tests for python3 compatibility
+    platform: linux64/opt
+    treeherder:
+        symbol: py(3)
+        kind: test
+        tier: 2
+    worker-type: aws-provisioner-v1/gecko-t-linux-large
+    worker:
+        docker-image: {in-tree: "lint"}
+        max-run-time: 3600
+    run:
+        using: run-task
+        # this will evolve as we get closer and closer to python 3 compatibility. It may
+        # eventually be a mach command or shell script.
+        command: python3 -mcompileall python/ taskcluster/
+    when:
+        files-changed:
+            - '**/*.py'
--- a/taskcluster/docker/lint/system-setup.sh
+++ b/taskcluster/docker/lint/system-setup.sh
@ -15,6 +15,8 @@ apt_packages+=('locales')
 apt_packages+=('git')
 apt_packages+=('python')
 apt_packages+=('python-pip')
+apt_packages+=('python3')
+apt_packages+=('python3-pip')
 apt_packages+=('sudo')
 apt_packages+=('wget')
 apt_packages+=('xz-utils')
--- a/taskcluster/taskgraph/action.yml
+++ b/taskcluster/taskgraph/action.yml
@ -28,10 +28,10 @@ payload:
    GECKO_HEAD_REPOSITORY: '{{{head_repository}}}'
    GECKO_HEAD_REF: '{{head_ref}}'
    GECKO_HEAD_REV: '{{head_rev}}'
-    HG_STORE_PATH: /builds/worker/checkouts/hg-store
+    HG_STORE_PATH: /home/worker/checkouts/hg-store

  cache:
-    level-{{level}}-checkouts: /builds/worker/checkouts
+    level-{{level}}-checkouts: /home/worker/checkouts

  features:
    taskclusterProxy: true
@ -47,20 +47,20 @@ payload:
  maxRunTime: 1800

  command:
-    - /builds/worker/bin/run-task
-    - '--vcs-checkout=/builds/worker/checkouts/gecko'
+    - /home/worker/bin/run-task
+    - '--vcs-checkout=/home/worker/checkouts/gecko'
    - '--'
    - bash
    - -cx
    - >
-        cd /builds/worker/checkouts/gecko &&
-        ln -s /builds/worker/artifacts artifacts &&
+        cd /home/worker/checkouts/gecko &&
+        ln -s /home/worker/artifacts artifacts &&
        ./mach --log-no-times taskgraph {{action}} {{action_args}}

  artifacts:
    'public':
      type: 'directory'
-      path: '/builds/worker/artifacts'
+      path: '/home/worker/artifacts'
      expires: '{{#from_now}}7 days{{/from_now}}'

 extra:
--- a/taskcluster/taskgraph/test/test_cron_util.py
+++ b/taskcluster/taskgraph/test/test_cron_util.py
@ -17,38 +17,38 @@ from taskgraph.cron.util import (
 class TestMatchUtc(unittest.TestCase):

    def test_hour_minute(self):
-        params = {'time': datetime.datetime(2017, 01, 26, 16, 30, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 16, 30, 0)}
        self.assertFalse(match_utc(params, hour=4, minute=30))
        self.assertTrue(match_utc(params, hour=16, minute=30))
        self.assertFalse(match_utc(params, hour=16, minute=0))

    def test_hour_only(self):
-        params = {'time': datetime.datetime(2017, 01, 26, 16, 0, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 16, 0, 0)}
        self.assertFalse(match_utc(params, hour=0))
        self.assertFalse(match_utc(params, hour=4))
        self.assertTrue(match_utc(params, hour=16))
-        params = {'time': datetime.datetime(2017, 01, 26, 16, 15, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 16, 15, 0)}
        self.assertFalse(match_utc(params, hour=0))
        self.assertFalse(match_utc(params, hour=4))
        self.assertTrue(match_utc(params, hour=16))
-        params = {'time': datetime.datetime(2017, 01, 26, 16, 30, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 16, 30, 0)}
        self.assertFalse(match_utc(params, hour=0))
        self.assertFalse(match_utc(params, hour=4))
        self.assertTrue(match_utc(params, hour=16))
-        params = {'time': datetime.datetime(2017, 01, 26, 16, 45, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 16, 45, 0)}
        self.assertFalse(match_utc(params, hour=0))
        self.assertFalse(match_utc(params, hour=4))
        self.assertTrue(match_utc(params, hour=16))

    def test_minute_only(self):
-        params = {'time': datetime.datetime(2017, 01, 26, 13, 0, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 13, 0, 0)}
        self.assertTrue(match_utc(params, minute=0))
        self.assertFalse(match_utc(params, minute=15))
        self.assertFalse(match_utc(params, minute=30))
        self.assertFalse(match_utc(params, minute=45))

    def test_zeroes(self):
-        params = {'time': datetime.datetime(2017, 01, 26, 0, 0, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 0, 0, 0)}
        self.assertTrue(match_utc(params, minute=0))
        self.assertTrue(match_utc(params, hour=0))
        self.assertFalse(match_utc(params, hour=1))
@ -57,7 +57,7 @@ class TestMatchUtc(unittest.TestCase):
        self.assertFalse(match_utc(params, minute=45))

    def test_invalid_minute(self):
-        params = {'time': datetime.datetime(2017, 01, 26, 13, 0, 0)}
+        params = {'time': datetime.datetime(2017, 1, 26, 13, 0, 0)}
        self.assertRaises(Exception, lambda:
                          match_utc(params, minute=1))

--- a/taskcluster/taskgraph/test/test_util_parameterization.py
+++ b/taskcluster/taskgraph/test/test_util_parameterization.py
@ -17,7 +17,7 @@ from taskgraph.util.parameterization import (
 class TestTimestamps(unittest.TestCase):

    def test_no_change(self):
-        now = datetime.datetime(2018, 01, 01)
+        now = datetime.datetime(2018, 1, 1)
        input = {
            "key": "value",
            "numeric": 10,
@ -26,13 +26,13 @@ class TestTimestamps(unittest.TestCase):
        self.assertEqual(resolve_timestamps(now, input), input)

    def test_buried_replacement(self):
-        now = datetime.datetime(2018, 01, 01)
+        now = datetime.datetime(2018, 1, 1)
        input = {"key": [{"key2": [{'relative-datestamp': '1 day'}]}]}
        self.assertEqual(resolve_timestamps(now, input),
                         {"key": [{"key2": ['2018-01-02T00:00:00Z']}]})

    def test_appears_with_other_keys(self):
-        now = datetime.datetime(2018, 01, 01)
+        now = datetime.datetime(2018, 1, 1)
        input = [{'relative-datestamp': '1 day', 'another-key': True}]
        self.assertEqual(resolve_timestamps(now, input),
                         [{'relative-datestamp': '1 day', 'another-key': True}])
--- a/taskcluster/taskgraph/test/test_util_schema.py
+++ b/taskcluster/taskgraph/test/test_util_schema.py
@ -27,7 +27,7 @@ class TestValidateSchema(unittest.TestCase):
        try:
            validate_schema(schema, {'x': 'not-int'}, "pfx")
            self.fail("no exception raised")
-        except Exception, e:
+        except Exception as e:
            self.failUnless(str(e).startswith("pfx\n"))


--- a/testing/firefox-ui/tests/functional/sessionstore/test_tabbar_session_restore_button.py
+++ b/testing/firefox-ui/tests/functional/sessionstore/test_tabbar_session_restore_button.py
@ -7,9 +7,9 @@ from marionette_driver import Wait


 class TestBaseTabbarSessionRestoreButton(PuppeteerMixin, MarionetteTestCase):
-    def setUp(self, prefValue=True):
+    def setUp(self, restore_button_pref=1):
        super(TestBaseTabbarSessionRestoreButton, self).setUp()
-        self.marionette.enforce_gecko_prefs({'browser.tabs.restorebutton': prefValue})
+        self.marionette.enforce_gecko_prefs({'browser.tabs.restorebutton': restore_button_pref})

        # Each list element represents a window of tabs loaded at
        # some testing URL, the URLS are arbitrary.
@ -96,7 +96,7 @@ class TestTabbarSessionRestoreButton(TestBaseTabbarSessionRestoreButton):

 class TestNoTabbarSessionRestoreButton(TestBaseTabbarSessionRestoreButton):
    def setUp(self):
-        super(TestNoTabbarSessionRestoreButton, self).setUp(False)
+        super(TestNoTabbarSessionRestoreButton, self).setUp(restore_button_pref=0)

    def test_pref_off_button_does_not_show(self):
        wrapper = self.puppeteer.windows.current.tabbar.restore_tabs_button_wrapper
--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@ -417,7 +417,10 @@ class MochitestServer(object):
        # get testing environment
        env = test_environment(xrePath=self._xrePath, log=self._log)
        env["XPCOM_DEBUG_BREAK"] = "warn"
-        env["LD_LIBRARY_PATH"] = self._xrePath
+        if "LD_LIBRARY_PATH" not in env or env["LD_LIBRARY_PATH"] is None:
+            env["LD_LIBRARY_PATH"] = self._xrePath
+        else:
+            env["LD_LIBRARY_PATH"] = ":".join([self._xrePath, env["LD_LIBRARY_PATH"]])

        # When running with an ASan build, our xpcshell server will also be ASan-enabled,
        # thus consuming too much resources when running together with the browser on
--- a/toolkit/components/extensions/ExtensionCommon.jsm
+++ b/toolkit/components/extensions/ExtensionCommon.jsm
@ -1500,9 +1500,7 @@ LocaleData.prototype = {


  get uiLocale() {
-    // Return the browser locale, but convert it to a Chrome-style
-    // locale code.
-    return Services.locale.getAppLocaleAsBCP47().replace(/-/g, "_");
+    return Services.locale.getAppLocaleAsBCP47();
  },
 };

--- a/toolkit/components/extensions/ExtensionPreferencesManager.jsm
+++ b/toolkit/components/extensions/ExtensionPreferencesManager.jsm
@ -296,6 +296,19 @@ this.ExtensionPreferencesManager = {
    await Promise.all(removePromises);
  },

+  /**
+   * Return the currently active value for a setting.
+   *
+   * @param {string} name
+   *        The unique id of the setting.
+   *
+   * @returns {Object} The current setting object.
+   */
+  async getSetting(name) {
+    await ExtensionSettingsStore.initialize();
+    return ExtensionSettingsStore.getSetting(STORE_TYPE, name);
+  },
+
  /**
   * Return the levelOfControl for a setting / extension combo.
   * This queries the levelOfControl from the ExtensionSettingsStore and also
@ -305,17 +318,24 @@ this.ExtensionPreferencesManager = {
   *        The extension for which levelOfControl is being requested.
   * @param {string} name
   *        The unique id of the setting.
+   * @param {string} storeType
+   *        The name of the store in ExtensionSettingsStore.
+   *        Defaults to STORE_TYPE.
   *
   * @returns {Promise}
   *          Resolves to the level of control of the extension over the setting.
   */
-  async getLevelOfControl(extension, name) {
-    for (let prefName of settingsMap.get(name).prefNames) {
-      if (Preferences.locked(prefName)) {
-        return "not_controllable";
+  async getLevelOfControl(extension, name, storeType = STORE_TYPE) {
+    // This could be called for a setting that isn't defined to the PreferencesManager,
+    // in which case we simply defer to the SettingsStore.
+    if (storeType === STORE_TYPE) {
+      for (let prefName of settingsMap.get(name).prefNames) {
+        if (Preferences.locked(prefName)) {
+          return "not_controllable";
+        }
      }
    }
    await ExtensionSettingsStore.initialize();
-    return ExtensionSettingsStore.getLevelOfControl(extension, STORE_TYPE, name);
+    return ExtensionSettingsStore.getLevelOfControl(extension, storeType, name);
  },
 };
--- a/toolkit/components/extensions/ext-browserSettings.js
+++ b/toolkit/components/extensions/ext-browserSettings.js
@ -2,28 +2,38 @@
 /* vim: set sts=2 sw=2 et tw=80: */
 "use strict";

+XPCOMUtils.defineLazyModuleGetter(this, "ExtensionSettingsStore",
+                                  "resource://gre/modules/ExtensionSettingsStore.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Preferences",
                                  "resource://gre/modules/Preferences.jsm");

 Cu.import("resource://gre/modules/ExtensionPreferencesManager.jsm");

-const getSettingsAPI = (extension, name, callback) => {
+const HOMEPAGE_OVERRIDE_SETTING = "homepage_override";
+const URL_STORE_TYPE = "url_overrides";
+const NEW_TAB_OVERRIDE_SETTING = "newTabURL";
+
+const getSettingsAPI = (extension, name, callback, storeType, readOnly = false) => {
  return {
    async get(details) {
      return {
        levelOfControl: details.incognito ?
          "not_controllable" :
          await ExtensionPreferencesManager.getLevelOfControl(
-            extension, name),
+            extension, name, storeType),
        value: await callback(),
      };
    },
    set(details) {
-      return ExtensionPreferencesManager.setSetting(
-        extension, name, details.value);
+      if (!readOnly) {
+        return ExtensionPreferencesManager.setSetting(
+          extension, name, details.value);
+      }
    },
    clear(details) {
-      return ExtensionPreferencesManager.removeSetting(extension, name);
+      if (!readOnly) {
+        return ExtensionPreferencesManager.removeSetting(extension, name);
+      }
    },
  };
 };
@ -73,6 +83,25 @@ this.browserSettings = class extends ExtensionAPI {
            return Preferences.get("browser.cache.disk.enable") &&
              Preferences.get("browser.cache.memory.enable");
          }),
+        homepageOverride: getSettingsAPI(extension,
+          HOMEPAGE_OVERRIDE_SETTING,
+          async () => {
+            let homepageSetting = await ExtensionPreferencesManager.getSetting(HOMEPAGE_OVERRIDE_SETTING);
+            if (homepageSetting) {
+              return homepageSetting.value;
+            }
+            return null;
+          }, undefined, true),
+        newTabPageOverride: getSettingsAPI(extension,
+          NEW_TAB_OVERRIDE_SETTING,
+          async () => {
+            await ExtensionSettingsStore.initialize();
+            let newTabPageSetting = ExtensionSettingsStore.getSetting(URL_STORE_TYPE, NEW_TAB_OVERRIDE_SETTING);
+            if (newTabPageSetting) {
+              return newTabPageSetting.value;
+            }
+            return null;
+          }, URL_STORE_TYPE, true),
      },
    };
  }
--- a/toolkit/components/extensions/schemas/browser_settings.json
+++ b/toolkit/components/extensions/schemas/browser_settings.json
@ -29,6 +29,14 @@
      "cacheEnabled": {
        "$ref": "types.Setting",
        "description": "Enables or disables the browser cache."
+      },
+      "homepageOverride": {
+        "$ref": "types.Setting",
+        "description": "Returns the value of the overridden home page. Read-only."
+      },
+      "newTabPageOverride": {
+        "$ref": "types.Setting",
+        "description": "Returns the value of the overridden new tab page. Read-only."
      }
    }
  }
--- a/toolkit/components/extensions/test/xpcshell/test_ext_extensionPreferencesManager.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_extensionPreferencesManager.js
@ -119,6 +119,9 @@ add_task(async function test_preference_manager() {
      "controlled_by_this_extension",
      "getLevelOfControl returns correct levelOfControl when a pref has been set.");

+    let checkSetting = await ExtensionPreferencesManager.getSetting(setting);
+    equal(checkSetting.value, newValue1, "getSetting returns the expected value.");
+
    let newValue2 = "newValue2";
    prefsChanged = await ExtensionPreferencesManager.setSetting(extensions[0], setting, newValue2);
    ok(!prefsChanged, "setSetting returns false when the pref(s) have not been set.");
@ -166,6 +169,9 @@ add_task(async function test_preference_manager() {
      equal(Preferences.get(settingObj.prefNames[i]), settingObj.initalValues[i],
        "removeSetting sets the pref(s) to the initial value(s) when removing the last extension.");
    }
+
+    checkSetting = await ExtensionPreferencesManager.getSetting(setting);
+    equal(checkSetting, null, "getSetting returns null when nothing has been set.");
  }

  // Tests for unsetAll.
--- a/toolkit/components/extensions/test/xpcshell/test_ext_i18n.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_i18n.js
@ -370,7 +370,7 @@ add_task(async function test_get_ui_language() {
  await extension.startup();
  await extension.awaitMessage("content-loaded");

-  extension.sendMessage(["expect-results", "en_US"]);
+  extension.sendMessage(["expect-results", "en-US"]);

  await extension.awaitMessage("background-done");
  await extension.awaitMessage("content-done");
--- a/toolkit/components/extensions/test/xpcshell/test_ext_i18n_css.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_i18n_css.js
@ -115,7 +115,7 @@ async function test_i18n_css(options = {}) {
  cssURL = cssURL.replace(/foo.css$/, "locale.css");

  css = await fetch(cssURL);
-  equal(css, '* { content: "en_US ltr rtl left right" }', "CSS file localized in mochitest scope");
+  equal(css, '* { content: "en-US ltr rtl left right" }', "CSS file localized in mochitest scope");

  // We don't currently have a good way to mock this.
  if (false) {
--- a/toolkit/components/telemetry/Scalars.yaml
+++ b/toolkit/components/telemetry/Scalars.yaml
@ -277,6 +277,90 @@ browser.usage:
      - 'main'
      - 'content'

+# The following section contains the session restore scalars.
+browser.session.restore:
+  number_of_win:
+    bug_numbers:
+      - 1379226
+    description: The count of windows open after a session has been restored.
+    expires: never
+    kind: uint
+    notification_emails:
+      - bwinton@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
+  number_of_tabs:
+    bug_numbers:
+      - 1379226
+    description: The count of tabs open after a session has been restored.
+    expires: never
+    kind: uint
+    notification_emails:
+      - bwinton@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
+  tabbar_restore_available:
+    bug_numbers:
+      - 1379226
+    description: >
+      Recorded on startup. Boolean stating whether the tabbar session
+      restore button was ever available.
+    expires: never
+    kind: boolean
+    notification_emails:
+      - bwinton@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
+  tabbar_restore_clicked:
+    bug_numbers:
+      - 1379226
+    description: >
+      Recorded on click event. Boolean stating if the session restore button
+      was clicked.
+    expires: never
+    kind: boolean
+    notification_emails:
+      - bwinton@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
+  browser_startup_page:
+    bug_numbers:
+      - 1379226
+    description: >
+      The value of the browser.startup.page pref.
+      This pref restores the tabs and windows automatically when set to 3.
+    expires: never
+    kind: uint
+    notification_emails:
+      - bwinton@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
+  browser_tabs_restorebutton:
+    bug_numbers:
+      - 1379226
+    description: >
+      The value of the browser.tabs.restorebutton pref.
+      0 - the user is not a part of the experiment
+      1 - the user is a part of the experiment
+      2 - the user is part of the control group
+    expires: never
+    kind: uint
+    notification_emails:
+      - bwinton@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
 # This section is for probes used to measure use of the Webextensions storage.sync API.
 storage.sync.api.usage:
  extensions_using:
--- a/tools/tryselect/vcs.py
+++ b/tools/tryselect/vcs.py
@ -148,7 +148,7 @@ class HgHelper(VCSHelper):
    @property
    def files_changed(self):
        return self.run(['hg', 'log', '-r', '::. and not public()',
-                         '--template', '{join(files, "\n")}\n'])
+                         '--template', '{join(files, "\n")}\n']).splitlines()

    @property
    def has_uncommitted_changes(self):
--- a/xpcom/threads/Scheduler.cpp
+++ b/xpcom/threads/Scheduler.cpp
@ -477,7 +477,9 @@ SchedulerImpl::CreateQueue(nsIIdlePeriod* aIdlePeriod, nsThread** aThread)
  // Setup "main" thread
  mainThread = new nsThread(WrapNotNull(synchronizedQueue), nsThread::MAIN_THREAD, 0);

+#ifndef RELEASE_OR_BETA
  prioritized->SetNextIdleDeadlineRef(mainThread->NextIdleDeadlineRef());
+#endif

  mainThread.forget(aThread);
  return synchronizedQueue.forget();