[Media Galleries] Lazily initialize the storage monitor.

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 64 matching lines @@
   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.
   MediaGalleriesPreferences* GetPreferences(Profile* profile);
 
   // RemovableStorageObserver implementation.
   virtual void OnRemovableStorageDetached(const StorageInfo& info) OVERRIDE;
 
   size_t GetExtensionGalleriesHostCountForTests() const;
 
   // See TransientDeviceIds::GetTransientIdForDeviceId().
   uint64 GetTransientIdForDeviceId(const std::string& device_id);
 
@@ skipping 39 matching lines @@
   MTPDeviceDelegateMap mtp_device_delegate_map_;
 
   scoped_ptr<MediaFileSystemContext> file_system_context_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaFileSystemRegistry);
 };
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_FILE_SYSTEM_REGISTRY_H_