Media Galleries API: Fix MediaGalleriesPreferences finders race.

chrome/browser/media_galleries/media_file_system_registry.h

 // 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.
 
 // MediaFileSystemRegistry registers pictures directories and media devices as
 // File API filesystems and keeps track of the path to filesystem ID mappings.
 
 #ifndef CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_FILE_SYSTEM_REGISTRY_H_
 #define CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_FILE_SYSTEM_REGISTRY_H_
 
@@ skipping 58 matching lines @@
   MediaFileSystemRegistry();
   virtual ~MediaFileSystemRegistry();
 
   // Passes to |callback| the list of media filesystem IDs and paths for a
   // given RVH. Called on the UI thread.
   void GetMediaFileSystemsForExtension(
       const content::RenderViewHost* rvh,
       const extensions::Extension* extension,
       const MediaFileSystemsCallback& callback);
 
-  // Returns the initialized media galleries preferences for the specified
-  // |profile|. This method should be used instead of calling
-  // MediaGalleriesPreferences directly because this method also ensures that
-  // currently attached removable devices are added to the preferences.
-  // Called on the UI thread.
-  // Note: Caller must ensure that the storage monitor is initialized before
-  // calling this method.
+  // Returns the media galleries preferences for the specified |profile|.
+  // Called on the UI thread. Caller is responsible for ensuring that the
+  // preferences are initialized before use.
   MediaGalleriesPreferences* GetPreferences(Profile* profile);
 
   // RemovableStorageObserver implementation.
   virtual void OnRemovableStorageDetached(const StorageInfo& info) OVERRIDE;
 
  private:
   friend class MediaFileSystemRegistryTest;
   friend class TestMediaFileSystemContext;
   class MediaFileSystemContextImpl;
 
@@ skipping 33 matching lines @@
 
   // Only accessed on the UI thread.
   MTPDeviceDelegateMap mtp_device_delegate_map_;
 
   scoped_ptr<MediaFileSystemContext> file_system_context_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaFileSystemRegistry);
 };
 
 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_FILE_SYSTEM_REGISTRY_H_