Media Galleries API: Fix MediaGalleriesPreferences finders race.

chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc

Index: chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc
diff --git a/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc
index e62718e48757d82d757120f6dcdde505bd039f38..d60718fbbe0210b17f923c54b2e573e2f87f2087 100644
--- a/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc
+++ b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.cc
@@ -82,16 +82,16 @@ GalleryWatchStateTracker::GalleryWatchStateTracker(Profile* profile)
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED,
                  content::Source<Profile>(profile_));
   MediaGalleriesPreferences* preferences =
-      g_browser_process->media_file_system_registry()->GetPreferences(
-          profile);
+      g_browser_process->media_file_system_registry()->GetPreferences(profile);
+  DCHECK(preferences->IsInitialized());
   preferences->AddGalleryChangeObserver(this);
 }
 
 GalleryWatchStateTracker::~GalleryWatchStateTracker() {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   MediaGalleriesPreferences* preferences =
-      g_browser_process->media_file_system_registry()->GetPreferences(
-          profile_);
+      g_browser_process->media_file_system_registry()->GetPreferences(profile_);
+  DCHECK(preferences->IsInitialized());

[vandebo (ex-Chrome), 2013/09/23 18:35:13]

nit: this isn't really needed; aside from being in a place where we know it must
already be initialized, the remaining code in this method doesn't need it to be
initialized.

[tommycli, 2013/09/23 20:39:12]

Done.

   preferences->RemoveGalleryChangeObserver(this);
 }
 
@@ -260,6 +260,7 @@ void GalleryWatchStateTracker::ReadFromStorage(
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   MediaGalleriesPreferences* preferences =
       g_browser_process->media_file_system_registry()->GetPreferences(profile_);
+  DCHECK(preferences->IsInitialized());

[vandebo (ex-Chrome), 2013/09/23 18:35:13]

Since this is the only place we actually use preferences, this is probably the
only place that it needs to be changed.

[tommycli, 2013/09/23 20:39:12]

Done.

   base::ListValue* list = NULL;
   if (!value.get() || !value->GetAsList(&list))
     return;