Media Galleries API: Fix MediaGalleriesPreferences finders race.

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

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // GalleryWatchStateTracker implementation.
 
 #include "chrome/browser/extensions/api/media_galleries_private/gallery_watch_state_tracker.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
@@ skipping 64 matching lines @@
 
 GalleryWatchStateTracker::GalleryWatchStateTracker(Profile* profile)
     : profile_(profile) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   DCHECK(profile_);
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LOADED,
                  content::Source<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());
   preferences->RemoveGalleryChangeObserver(this);
 }
 
 // static
 GalleryWatchStateTracker* GalleryWatchStateTracker::GetForProfile(
     Profile* profile) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 #if defined(OS_WIN)
   // Gallery watch operation is supported only on windows.
   // Please refer to crbug.com/144491 for more details.
@@ skipping 148 matching lines @@
       kRegisteredGalleryWatchers,
       WatchedGalleryIdsToValue(gallery_ids).PassAs<base::Value>());
 }
 
 void GalleryWatchStateTracker::ReadFromStorage(
     const std::string& extension_id,
     scoped_ptr<base::Value> value) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   MediaGalleriesPreferences* preferences =
       g_browser_process->media_file_system_registry()->GetPreferences(profile_);
+  DCHECK(preferences->IsInitialized());
   base::ListValue* list = NULL;
   if (!value.get() || !value->GetAsList(&list))
     return;
   MediaGalleryPrefIdSet gallery_ids = WatchedGalleryIdsFromValue(list);
   if (gallery_ids.empty())
     return;
 
   for (MediaGalleryPrefIdSet::const_iterator id_iter = gallery_ids.begin();
        id_iter != gallery_ids.end(); ++id_iter) {
     watched_extensions_map_[extension_id][*id_iter] = false;
@@ skipping 75 matching lines @@
     const std::string& extension_id,
     MediaGalleryPrefId gallery_id) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   if (HasGalleryWatchInfo(extension_id, gallery_id, true))
     return false;
   watched_extensions_map_[extension_id][gallery_id] = true;
   return true;
 }
 
 }  // namespace extensions