[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 4687e7d6951cfb270dfddeabac2849dcb644fe07..6c95e67241cdb91b26f6052304ff2c27e4b80d0a 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/media_galleries_preferences.h"
 #include "chrome/browser/media_galleries/mtp_device_delegate_impl.h"
@@ -65,7 +66,8 @@ struct MediaFileSystemInfo {
 typedef base::Callback<void(const std::vector<MediaFileSystemInfo>&)>
     MediaFileSystemsCallback;
 
-class MediaFileSystemRegistry : public RemovableStorageObserver {
+class MediaFileSystemRegistry : public RemovableStorageObserver,
+                                public MediaGalleriesPreferences::Vendor {
  public:
   MediaFileSystemRegistry();
   virtual ~MediaFileSystemRegistry();
@@ -73,16 +75,19 @@ class MediaFileSystemRegistry : public RemovableStorageObserver {
   // 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,
+      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
+  // Call the given callback with preferences. This is asynchronous so that
+  // StorageMonitor may be initialized lazily in order to set up the returned
+  // preferences vendor.
+  // 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(
+      base::Callback<void(MediaGalleriesPreferences::Vendor*)> callback);
 
   // RemovableStorageObserver implementation.
   virtual void OnRemovableStorageDetached(const StorageInfo& info) OVERRIDE;
@@ -92,10 +97,25 @@ class MediaFileSystemRegistry : public RemovableStorageObserver {
   // See TransientDeviceIds::GetTransientIdForDeviceId().
   uint64 GetTransientIdForDeviceId(const std::string& device_id);
 
+  // MediaGalleriesPreferences::Vendor
+  virtual MediaGalleriesPreferences* GetPreferences(Profile* profile) OVERRIDE;
+
  private:
   friend class TestMediaFileSystemContext;
   class MediaFileSystemContextImpl;
 
+  // Bottom half of |GetMediaFileSystemsForExtensions|, called after the
+  // StorageMonitor is initialized.
+  void GetMediaFileSystemsWithPreferences(
+      const content::RenderViewHost* rvh,
+      const extensions::Extension* extension,
+      const MediaFileSystemsCallback& callback,
+      MediaGalleriesPreferences::Vendor* vendor);
+
+  // Notify the registry when the storage monitor has been initialized.
+  void OnStorageMonitorInitialized(
+      base::Callback<void(MediaGalleriesPreferences::Vendor*)> callback);
+
   // Map an extension to the ExtensionGalleriesHost.
   typedef std::map<std::string /*extension_id*/,
                    scoped_refptr<ExtensionGalleriesHost> > ExtensionHostMap;
@@ -135,6 +155,8 @@ class MediaFileSystemRegistry : public RemovableStorageObserver {
 
   scoped_ptr<MediaFileSystemContext> file_system_context_;
 
+  base::WeakPtrFactory<MediaFileSystemRegistry> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaFileSystemRegistry);
 };