Push API: use an enum to indicate status.

content/public/browser/push_messaging_service.h

 // Copyright 2014 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 CONTENT_PUBLIC_BROWSER_PUSH_MESSAGING_SERVICE_H_
 #define CONTENT_PUBLIC_BROWSER_PUSH_MESSAGING_SERVICE_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "content/common/content_export.h"
+#include "content/public/common/push_messaging_status.h"
 #include "url/gurl.h"
 
 namespace content {
 
 // A push service-agnostic interface that the Push API uses for talking to
 // push messaging services like GCM.
 class CONTENT_EXPORT PushMessagingService {
  public:
   typedef base::Callback<void(const GURL& /* endpoint */,
                               const std::string& /* registration_id */,
-                              bool /* success */)>
+                              PushMessagingStatus /* status */)>
       RegisterCallback;
 
   virtual ~PushMessagingService() {}
   virtual void Register(const std::string& app_id,
                         const std::string& sender_id,
                         int renderer_id,
                         int render_frame_id,
                         bool user_gesture,
                         const RegisterCallback& callback) = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_PUSH_MESSAGING_SERVICE_H_