[GCM] Reland: Introduce GCMClientFactory to create GCMClient for GCMProfileService

chrome/browser/services/gcm/gcm_client_factory.h

+// Copyright (c) 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 CHROME_BROWSER_SERVICES_GCM_GCM_CLIENT_FACTORY_H_
+#define CHROME_BROWSER_SERVICES_GCM_GCM_CLIENT_FACTORY_H_
+
+#include "base/macros.h"
+
+class Profile;
+
+namespace gcm {
+
+class GCMClient;
+
+class GCMClientFactory {
+ public:
+  static GCMClient* GetClient();
+
+  // Passes a mocked instance for testing purpose.
+  typedef GCMClient* (*TestingFactoryFunction)();
+  static void SetTestingFactory(TestingFactoryFunction factory);
+
+ private:
+  GCMClientFactory();
+  ~GCMClientFactory();
+
+  DISALLOW_COPY_AND_ASSIGN(GCMClientFactory);
+};
+
+}  // namespace gcm
+
+#endif  // CHROME_BROWSER_SERVICES_GCM_GCM_CLIENT_FACTORY_H_