Backed out 4 changesets (bug 1470280) for browser-chrome failure in...

Backed out 4 changesets (bug 1470280) for browser-chrome failure in layout/xul/test/browser_bug703210.js. a=backout

Backed out changeset 72e7ef77480d (bug 1470280)
Backed out changeset 403c3d0daf6a (bug 1470280)
Backed out changeset fe7ccd9fee76 (bug 1470280)
Backed out changeset 60699c2387f6 (bug 1470280)

browser/base/content/test/performance/browser_preferences_usage.js

 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
-const DEFAULT_PROCESS_COUNT = Services.prefs.getDefaultBranch(null).getIntPref("dom.ipc.processCount");
-
 /**
  * A test that checks whether any preference getter from the given list
  * of stats was called more often than the max parameter.
@@ -122,10 +120,7 @@ add_task(async function startup() {
 
 // This opens 10 tabs and checks pref getters.
 add_task(async function open_10_tabs() {
-  // This is somewhat arbitrary. When we had a default of 4 content processes
-  // the value was 15. We need to scale it as we increase the number of
-  // content processes so we approximate with 4 * process_count.
-  const max = 4 * DEFAULT_PROCESS_COUNT;
+  let max = 15;
 
   let whitelist = {
     "layout.css.dpi": {
@@ -151,6 +146,10 @@ add_task(async function open_10_tabs() {
       min: 10,
       max: 18,
     },
+    "dom.ipc.processCount": {
+      min: 10,
+      max: 15,
+    },
     "browser.startup.record": {
       max: 20,
     },

browser/components/extensions/test/browser/browser_ext_slow_script.js

@@ -2,8 +2,6 @@
 /* vim: set sts=2 sw=2 et tw=80: */
 "use strict";
 
-const DEFAULT_PROCESS_COUNT = Services.prefs.getDefaultBranch(null).getIntPref("dom.ipc.processCount");
-
 add_task(async function test_slow_content_script() {
   // Make sure we get a new process for our tab, or our reportProcessHangs
   // preferences value won't apply to it.
@@ -17,7 +15,7 @@ add_task(async function test_slow_content_script() {
 
   await SpecialPowers.pushPrefEnv({
     set: [
-      ["dom.ipc.processCount", DEFAULT_PROCESS_COUNT * 2],
+      ["dom.ipc.processCount", 8],
       ["dom.ipc.processPrelaunch.enabled", false],
       ["dom.ipc.reportProcessHangs", true],
     ],

browser/components/preferences/in-content/main.xul

@@ -613,7 +613,6 @@
           <menuitem label="5" value="5"/>
           <menuitem label="6" value="6"/>
           <menuitem label="7" value="7"/>
-          <menuitem label="8" value="8"/>
         </menupopup>
       </menulist>
     </hbox>

browser/components/preferences/in-content/tests/browser_performance_e10srollout.js

@@ -44,9 +44,7 @@ add_task(async function testPrefsAreDefault() {
 });
 
 add_task(async function testPrefsSetByUser() {
-  const kNewCount = DEFAULT_PROCESS_COUNT - 2;
-
-  Services.prefs.setIntPref("dom.ipc.processCount", kNewCount);
+  Services.prefs.setIntPref("dom.ipc.processCount", DEFAULT_PROCESS_COUNT + 2);
   Services.prefs.setBoolPref("browser.preferences.defaultPerformanceSettings.enabled", false);
 
   let prefs = await openPreferencesViaOpenPreferencesAPI("paneGeneral", {leaveOpen: true});
@@ -58,8 +56,8 @@ add_task(async function testPrefsSetByUser() {
 
   let contentProcessCount = doc.querySelector("#contentProcessCount");
   is(contentProcessCount.disabled, false, "process count control should be enabled");
-  is(Services.prefs.getIntPref("dom.ipc.processCount"), kNewCount, "process count should be the set value");
-  is(contentProcessCount.selectedItem.value, kNewCount, "selected item should be the set one");
+  is(Services.prefs.getIntPref("dom.ipc.processCount"), DEFAULT_PROCESS_COUNT + 2, "process count should be the set value");
+  is(contentProcessCount.selectedItem.value, DEFAULT_PROCESS_COUNT + 2, "selected item should be the set one");
 
   let useRecommendedPerformanceSettings = doc.querySelector("#useRecommendedPerformanceSettings");
   useRecommendedPerformanceSettings.click();

dom/base/test/browser_force_process_selector.js

@@ -5,11 +5,14 @@ const CONTENT_CREATED = "ipc:content-created";
 // Make sure that BTU.withNewTab({ ..., forceNewProcess: true }) loads
 // new tabs in their own process.
 async function spawnNewAndTest(recur, pids) {
+  let processCreated = TestUtils.topicObserved(CONTENT_CREATED);
   await BrowserTestUtils.withNewTab({ gBrowser, url: "about:blank", forceNewProcess: true },
                                     async function(browser) {
-      // Make sure our new browser is in its own process.
+      // Make sure our new browser is in its own process. The processCreated
+      // promise should have already resolved by this point.
+      await processCreated;
       let newPid = browser.frameLoader.tabParent.osPid;
-      ok(!pids.has(newPid), "new tab is in its own process: " + recur);
+      ok(!pids.has(newPid), "new tab is in its own process");
       pids.add(newPid);
 
       if (recur) {

modules/libpref/init/all.js

@@ -3284,11 +3284,7 @@ pref("dom.ipc.plugins.asyncdrawing.enabled", true);
 pref("dom.ipc.plugins.forcedirect.enabled", true);
 
 // Enable multi by default.
-#if defined(NIGHTLY_BUILD)
-pref("dom.ipc.processCount", 8);
-#else
 pref("dom.ipc.processCount", 4);
-#endif
 
 // Default to allow only one file:// URL content process.
 pref("dom.ipc.processCount.file", 1);