Bug 1596738 - Don't focus the tab's content area for restores triggered by DocumentChannel process switches, r=dao,nika,mixedpuppy

This causes the browser to steal focus from any element that was focused prior
to the completion of the remoteness flip. This is particularly a problem for
fission because every cross-origin navigation requires a process switch.

This code is still necessary for "normal" session restores (see bug 1410591),
but focus is handled elsewhere for remote navigations.

Differential Revision: https://phabricator.services.mozilla.com/D82783

accessible/tests/browser/events/browser_test_textcaret.js

@@ -20,6 +20,7 @@ async function checkURLBarCaretEvents() {
   const kURL = "about:mozilla";
   let newWin = await BrowserTestUtils.openNewBrowserWindow();
   BrowserTestUtils.loadURI(newWin.gBrowser.selectedBrowser, kURL);
+  newWin.gBrowser.selectedBrowser.focus();
 
   await waitForEvent(EVENT_DOCUMENT_LOAD_COMPLETE, event => {
     try {

browser/base/content/test/general/browser.ini

@@ -401,7 +401,6 @@ tags = fullscreen
 [browser_newWindowDrop.js]
 # DO NOT ADD MORE TESTS HERE. USE A TOPICAL DIRECTORY INSTEAD.
 [browser_newwindow_focus.js]
-fail-if = fission # URLBar should be focused - [object XULFrameElement] == {} - JS frame :: chrome://mochitests/content/browser/browser/base/content/test/general/browser_newwindow_focus.js :: test_no_steal_focus/< :: line 113
 skip-if = os == "linux" && !e10s # Bug 1263254 - Perma fails on Linux without e10s for some reason.
 # DO NOT ADD MORE TESTS HERE. USE A TOPICAL DIRECTORY INSTEAD.
 [browser_bug1299667.js]

browser/components/extensions/test/browser/browser_ext_commands_onCommand.js

@@ -188,6 +188,15 @@ add_task(async function test_user_defined_commands() {
   await BrowserTestUtils.loadURI(win1.gBrowser.selectedBrowser, "about:robots");
   await BrowserTestUtils.browserLoaded(win1.gBrowser.selectedBrowser);
 
+  // We would have previously focused the window's content area after the
+  // navigation from about:blank to about:robots, but bug 1596738 changed this
+  // to prevent the browser element from stealing focus from the urlbar.
+  //
+  // Some of these command tests (specifically alt-a on linux) were designed
+  // based on focus being in the browser content, so we need to manually focus
+  // the browser here to preserve that assumption.
+  win1.gBrowser.selectedBrowser.focus();
+
   let commands = {};
   let isMac = AppConstants.platform == "macosx";
   let totalMacOnlyCommands = 0;
@@ -263,6 +272,9 @@ add_task(async function test_user_defined_commands() {
   await BrowserTestUtils.loadURI(win2.gBrowser.selectedBrowser, "about:robots");
   await BrowserTestUtils.browserLoaded(win2.gBrowser.selectedBrowser);
 
+  // See comment above.
+  win2.gBrowser.selectedBrowser.focus();
+
   let totalTestCommands =
     Object.keys(testCommands).length + numberNumericCommands;
   let expectedCommandsRegistered = isMac
@@ -302,6 +314,10 @@ add_task(async function test_user_defined_commands() {
     "about:robots"
   );
   await BrowserTestUtils.browserLoaded(privateWin.gBrowser.selectedBrowser);
+
+  // See comment above.
+  privateWin.gBrowser.selectedBrowser.focus();
+
   keyset = privateWin.document.getElementById(keysetID);
   is(keyset, null, "Expected keyset is not added to private windows");
 

browser/components/sessionstore/SessionStore.jsm

@@ -4943,8 +4943,13 @@ var SessionStoreInternal = {
         aOptions.restoreContentReason || RESTORE_TAB_CONTENT_REASON.SET_STATE,
     });
 
-    // Focus the tab's content area.
-    if (aTab.selected && !window.isBlankPageURL(uri)) {
+    // Focus the tab's content area, unless the restore is for a new tab URL or
+    // was triggered by a DocumentChannel process switch.
+    if (
+      aTab.selected &&
+      !window.isBlankPageURL(uri) &&
+      !aOptions.isRemotenessUpdate
+    ) {
       browser.focus();
     }
   },