[Media Galleries] Lazily initialize the storage monitor.

chrome/browser/media_galleries/media_file_system_registry.h

Index: chrome/browser/media_galleries/media_file_system_registry.h
diff --git a/chrome/browser/media_galleries/media_file_system_registry.h b/chrome/browser/media_galleries/media_file_system_registry.h
index 6843c3a0f87826bfbae243f8c4512987ddb54626..4d7eb92d150fe6467ca8b00ef17097d0a24695b0 100644
--- a/chrome/browser/media_galleries/media_file_system_registry.h
+++ b/chrome/browser/media_galleries/media_file_system_registry.h
@@ -16,6 +16,7 @@
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/prefs/pref_change_registrar.h"
 #include "chrome/browser/media_galleries/fileapi/mtp_device_file_system_config.h"
 #include "chrome/browser/media_galleries/media_galleries_preferences.h"
@@ -81,12 +82,16 @@ class MediaFileSystemRegistry : public RemovableStorageObserver {
       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
+  // Call the given callback with preferences. This is asynchronous so that
+  // StorageMonitor may be initialized lazily in order to set up the returned
+  // preferences.
+  // 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.
-  MediaGalleriesPreferences* GetPreferences(Profile* profile);
+  void GetPreferencesAsync(
+      Profile* profile,
+      base::Callback<void(MediaGalleriesPreferences*)> callback);
 
   // RemovableStorageObserver implementation.
   virtual void OnRemovableStorageDetached(const StorageInfo& info) OVERRIDE;
@@ -100,6 +105,21 @@ class MediaFileSystemRegistry : public RemovableStorageObserver {
   friend class TestMediaFileSystemContext;
   class MediaFileSystemContextImpl;
 
+  MediaGalleriesPreferences* GetPreferences(Profile* profile);
+
+  // Bottom half of |GetMediaFileSystemsForExtensions|, called after the
+  // StorageMonitor is initialized.
+  void GetMediaFileSystemsPostStorageMonitorInit(
+      const content::RenderViewHost* rvh,
+      const extensions::Extension* extension,
+      const MediaFileSystemsCallback& callback,
+      MediaGalleriesPreferences* preferences);
+
+  // Notify the registry when the storage monitor has been initialized.
+  void OnStorageMonitorInitialized(
+      Profile* profile,
+      base::Callback<void(MediaGalleriesPreferences*)> callback);
+
   // Map an extension to the ExtensionGalleriesHost.
   typedef std::map<std::string /*extension_id*/,
                    scoped_refptr<ExtensionGalleriesHost> > ExtensionHostMap;
@@ -145,6 +165,8 @@ class MediaFileSystemRegistry : public RemovableStorageObserver {
 
   scoped_ptr<MediaFileSystemContext> file_system_context_;
 
+  base::WeakPtrFactory<MediaFileSystemRegistry> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaFileSystemRegistry);
 };