Bug 1369399 - Re-enable e10s for DevEdition. r=Felipe

I thought of fixing this in the e10srollout addon because DevEdition is now
built off of Beta, but it would only serve to complicate the addon even more
and expose us to more risk every time we touch it. Also, DevEdition stayed on
the Aurora update channel and who knows if we're going to change that in the
future. Special casing DevEdition (via AppConstants) is possible, but it was
going to get messy pretty quickly. This is probably the most straightforward
way to make this all work.

MozReview-Commit-ID: 6WPjBawUutz

--HG--
extra : rebase_source : 156846085e1e3db7cd4924793a1de5d9336fab1c

browser/app/profile/firefox.js

@@ -997,10 +997,6 @@ pref("browser.flash-protected-mode-flip.done", false);
 
 pref("dom.ipc.shims.enabledWarnings", false);
 
-// Start the browser in e10s mode
-pref("browser.tabs.remote.autostart", false);
-pref("browser.tabs.remote.desktopbehavior", true);
-
 #if defined(XP_WIN) && defined(MOZ_SANDBOX)
 // Controls whether and how the Windows NPAPI plugin process is sandboxed.
 // To get a different setting for a particular plugin replace "default", with
@@ -1517,7 +1513,11 @@ pref("privacy.usercontext.about_newtab_segregation.enabled", false);
 pref("privacy.userContext.longPressBehavior", 0);
 #endif
 
-#ifndef RELEASE_OR_BETA
+// Start the browser in e10s mode
+pref("browser.tabs.remote.autostart", false);
+pref("browser.tabs.remote.desktopbehavior", true);
+
+#if !defined(RELEASE_OR_BETA) || defined(MOZ_DEV_EDITION)
 // At the moment, autostart.2 is used, while autostart.1 is unused.
 // We leave it here set to false to reset users' defaults and allow
 // us to change everybody to true in the future, when desired.

modules/libpref/init/all.js

@@ -3142,7 +3142,9 @@ pref("dom.ipc.plugins.asyncdrawing.enabled", true);
 // Force the accelerated direct path for a subset of Flash wmode values
 pref("dom.ipc.plugins.forcedirect.enabled", true);
 
-#ifdef RELEASE_OR_BETA
+// Enable multi by default for Nightly and DevEdition only.
+// For Beta and Release builds, multi is controlled by the e10srollout addon.
+#if defined(RELEASE_OR_BETA) && !defined(MOZ_DEV_EDITION)
 pref("dom.ipc.processCount", 1);
 #else
 pref("dom.ipc.processCount", 4);