Bug 789945: Part 4. Explicitly make some pref save be blocking calls. r=bsmedberg

MozReview-Commit-ID: 1MEp7o65HAV

--HG--
extra : rebase_source : b787c78253ad22b6fd4785e7a66f426af4f9b424

gfx/src/DriverCrashGuard.cpp

@@ -388,7 +388,7 @@ DriverCrashGuard::FlushPreferences()
   MOZ_ASSERT(XRE_IsParentProcess());
 
   if (nsIPrefService* prefService = Preferences::GetService()) {
-    prefService->SavePrefFile(nullptr);
+    static_cast<Preferences *>(prefService)->SavePrefFileBlocking();
   }
 }
 

modules/libpref/init/all.js

@@ -20,6 +20,8 @@
  *  - Computed values (e.g. 50 * 1024) don't work.
  */
 
+pref("preferences.allow.omt-write", true);
+
 pref("keyword.enabled", false);
 pref("general.useragent.locale", "chrome://global/locale/intl.properties");
 pref("general.useragent.compatMode.firefox", false);

toolkit/components/places/Database.cpp

@@ -812,7 +812,7 @@ Database::ForceCrashAndReplaceDatabase(const nsCString& aReason)
   Preferences::SetBool(PREF_FORCE_DATABASE_REPLACEMENT, true);
   // Ensure that prefs get saved, or we could crash before storing them.
   nsIPrefService* prefService = Preferences::GetService();
-  if (prefService && NS_SUCCEEDED(prefService->SavePrefFile(nullptr))) {
+  if (prefService && NS_SUCCEEDED(static_cast<Preferences *>(prefService)->SavePrefFileBlocking())) {
     // We could force an application restart here, but we'd like to get these
     // cases reported to us, so let's force a crash instead.
     MOZ_CRASH_UNSAFE_OOL(aReason.get());

toolkit/components/startup/nsAppStartup.cpp

@@ -914,7 +914,7 @@ nsAppStartup::TrackStartupCrashBegin(bool *aIsSafeModeNecessary)
   mIsSafeModeNecessary = (recentCrashes > maxResumedCrashes && maxResumedCrashes != -1);
 
   nsCOMPtr<nsIPrefService> prefs = Preferences::GetService();
-  rv = prefs->SavePrefFile(nullptr); // flush prefs to disk since we are tracking crashes
+  rv = static_cast<Preferences *>(prefs.get())->SavePrefFileBlocking(); // flush prefs to disk since we are tracking crashes
   NS_ENSURE_SUCCESS(rv, rv);
 
   GetAutomaticSafeModeNecessary(aIsSafeModeNecessary);
@@ -974,7 +974,10 @@ nsAppStartup::TrackStartupCrashEnd()
     if (NS_FAILED(rv)) NS_WARNING("Could not clear startup crash count.");
   }
   nsCOMPtr<nsIPrefService> prefs = Preferences::GetService();
-  rv = prefs->SavePrefFile(nullptr); // flush prefs to disk since we are tracking crashes
+  // save prefs to disk since we are tracking crashes.  This may be
+  // asynchronous, so a crash could sneak in that we would mistake for
+  // a start up crash. See bug 789945 and bug 1361262.
+  rv = prefs->SavePrefFile(nullptr);
 
   return rv;
 }

toolkit/xre/nsXREDirProvider.cpp

@@ -773,7 +773,10 @@ CreateContentProcessSandboxTempDir()
     nsCOMPtr<nsIPrefService> prefsvc = Preferences::GetService();
     if (!prefsvc || NS_FAILED((rv = prefsvc->SavePrefFile(nullptr)))) {
       // Again, if we fail to save the pref file we might not be able to clean
-      // up the temp directory, so don't create one.
+      // up the temp directory, so don't create one.  Note that in the case
+      // the preference values allows an off main thread save, the successful
+      // return from the call doesn't mean we actually saved the file.  See
+      // bug 1364496 for details.
       NS_WARNING("Failed to save pref file, cannot create temp dir.");
       return nullptr;
     }

widget/android/nsAppShell.cpp

@@ -194,9 +194,10 @@ public:
         // We really want to send a notification like profile-before-change,
         // but profile-before-change ends up shutting some things down instead
         // of flushing data
-        nsIPrefService* prefs = Preferences::GetService();
+        Preferences* prefs = static_cast<Preferences *>(Preferences::GetService());
         if (prefs) {
-            prefs->SavePrefFile(nullptr);
+            // Force a main thread blocking save
+            prefs->SavePrefFileBlocking();
         }
     }