Bug 1362493 - Let users with mpc=true addons into the multi experiment. r=Felipe

MozReview-Commit-ID: CwV4vukwrm9

--HG--
extra : rebase_source : 12ca3dd13fbf0657025fe5a3f4911cf8f1a1027f

browser/extensions/e10srollout/bootstrap.js

@@ -175,16 +175,16 @@ function defineCohort() {
   if (!(updateChannel in MULTI_BUCKETS) ||
       !eligibleForMulti ||
       userOptedIn.multi ||
-      disqualified ||
-      getAddonsDisqualifyForMulti()) {
+      disqualified) {
     Preferences.reset(PREF_E10S_PROCESSCOUNT + ".web");
     return;
   }
 
   // If we got here with a cohortPrefix, it must be "addons-set50allmpc-",
-  // and we know because of getAddonsDisqualifyForMulti that the addons that
-  // are installed must be web extensions.
-  if (cohortPrefix) {
+  // which means that there's at least one add-on installed. If
+  // getAddonsDisqualifyForMulti returns false, that means that all installed
+  // addons are webextension based, so note that in the cohort name.
+  if (cohortPrefix && !getAddonsDisqualifyForMulti()) {
     cohortPrefix = "webextensions-";
   }
 

toolkit/xre/nsAppRunner.cpp

@@ -5130,13 +5130,6 @@ GetMaxWebProcessCount()
     return std::max(1u, optInPrefValue);
   }
 
-  // If there are add-ons that would make the user's experience poor, don't
-  // use more than one web content process.
-  if (Preferences::GetBool("extensions.e10sMultiBlocksEnabling", false) &&
-      Preferences::GetBool("extensions.e10sMultiBlockedByAddons", false)) {
-    return 1;
-  }
-
   if (Preferences::HasUserValue("dom.ipc.processCount.web")) {
     // The user didn't opt in or out so read the .web version of the pref.
     return std::max(1, Preferences::GetInt("dom.ipc.processCount.web", 1));