Add a Create method to DesktopNotificationHandler and stubs for the notification objects.

chrome/browser/desktop_notification_handler.h

Index: chrome/browser/desktop_notification_handler.h
diff --git a/chrome/browser/desktop_notification_handler.h b/chrome/browser/desktop_notification_handler.h
index d956ec03bcce9c9406e232992fe11f87dbb7ec87..51ce7e8bbbc3096e9ad67dca8f64f75483d7c879 100644
--- a/chrome/browser/desktop_notification_handler.h
+++ b/chrome/browser/desktop_notification_handler.h
@@ -15,10 +15,12 @@ struct DesktopNotificationHostMsg_Show_Params;
 // coming in from the renderer.
 class DesktopNotificationHandler : public RenderViewHostObserver {
  public:
-  explicit DesktopNotificationHandler(RenderViewHost* render_view_host);
+  static DesktopNotificationHandler* Create(RenderViewHost* render_view_host);
   virtual ~DesktopNotificationHandler();
 
  private:
+  explicit DesktopNotificationHandler(RenderViewHost* render_view_host);
+
   // RenderViewHostObserver implementation.
   virtual bool OnMessageReceived(const IPC::Message& message);