Bug 1318491 - Disable new tab longpress containers menu for private browsing mode r=Gijs

MozReview-Commit-ID: Ldmya1q7eO9

--HG--
extra : rebase_source : e7f1ee3d167a458dcbd0794718b0b11b286e8d1e

browser/base/content/tabbrowser.xml

@@ -5401,7 +5401,8 @@
           switch (aTopic) {
             case "nsPref:changed":
               // This is the only pref observed.
-              let containersEnabled = Services.prefs.getBoolPref("privacy.userContext.enabled");
+              let containersEnabled = Services.prefs.getBoolPref("privacy.userContext.enabled")
+                                        && !PrivateBrowsingUtils.isWindowPrivate(window);
 
               const newTab = document.getElementById("new-tab-button");
               const newTab2 = document.getAnonymousElementByAttribute(this, "anonid", "tabs-newtab-button")

browser/components/contextualidentity/test/browser/browser_newtabButton.js

@@ -33,3 +33,18 @@ add_task(function* test() {
     yield BrowserTestUtils.removeTab(tab);
   }
 });
+
+
+add_task(function* test_private_mode() {
+  let privateWindow = yield BrowserTestUtils.openNewBrowserWindow({private: true});
+  let privateDocument = privateWindow.document;
+  let {tabContainer} = privateWindow.gBrowser;
+  let newTab = privateDocument.getAnonymousElementByAttribute(tabContainer, "anonid", "tabs-newtab-button");
+  let newTab2 = privateDocument.getElementById("new-tab-button");
+  // Check to ensure we are talking about the right button
+  ok(!!newTab.clientWidth, "new tab button should not be hidden");
+  ok(!newTab2.clientWidth, "overflow new tab button should be hidden");
+  let popup = privateDocument.getAnonymousElementByAttribute(newTab, "anonid", "newtab-popup");
+  ok(!popup, "new tab should not have a popup");
+  yield BrowserTestUtils.closeWindow(privateWindow);
+});