Use MediaGalleryPreferences directly in GalleryWatchStateTracker interface.

chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api.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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_MEDIA_GALLERIES_PRIVATE_MEDIA_GALLERIES_PRIVATE_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_MEDIA_GALLERIES_PRIVATE_MEDIA_GALLERIES_PRIVATE_API_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 56 matching lines @@
 
   // EventRouter::Observer implementation.
   virtual void OnListenerAdded(const EventListenerInfo& details) OVERRIDE;
 
   MediaGalleriesPrivateEventRouter* GetEventRouter();
   GalleryWatchStateTracker* GetGalleryWatchStateTracker();
 
  private:
   friend class ProfileKeyedAPIFactory<MediaGalleriesPrivateAPI>;
 
-  void MaybeInitializeEventRouter();
+  void MaybeInitializeEventRouterAndTracker();
 
   // ProfileKeyedAPI implementation.
   static const char* service_name() {
     return "MediaGalleriesPrivateAPI";
   }
   static const bool kServiceIsNULLWhileTesting = true;
 
   // Current profile.
   Profile* profile_;
 
-  GalleryWatchStateTracker tracker_;
+  scoped_ptr<GalleryWatchStateTracker> tracker_;
 
   // Created lazily on first access.
   scoped_ptr<MediaGalleriesPrivateEventRouter>
       media_galleries_private_event_router_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaGalleriesPrivateAPI);
 };
 
 // Implements the chrome.mediaGalleriesPrivate.addGalleryWatch method.
 class MediaGalleriesPrivateAddGalleryWatchFunction
@@ skipping 82 matching lines @@
  protected:
   virtual ~MediaGalleriesPrivateGetHandlersFunction();
 
   // AsyncExtensionFunction overrides.
   virtual bool RunImpl() OVERRIDE;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_MEDIA_GALLERIES_PRIVATE_MEDIA_GALLERIES_PRIVATE_API_H_