GCM: Make InstanceIDHandler implementations use protected inheritance

components/gcm_driver/gcm_driver_desktop.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 COMPONENTS_GCM_DRIVER_GCM_DRIVER_DESKTOP_H_
 #define COMPONENTS_GCM_DRIVER_GCM_DRIVER_DESKTOP_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 24 matching lines @@
 
 namespace gcm {
 
 class GCMAccountMapper;
 class GCMAppHandler;
 class GCMClientFactory;
 class GCMDelayedTaskController;
 
 // GCMDriver implementation for desktop and Chrome OS, using GCMClient.
 class GCMDriverDesktop : public GCMDriver,
-                         public InstanceIDHandler {
+                         protected InstanceIDHandler {
  public:
   GCMDriverDesktop(
       std::unique_ptr<GCMClientFactory> gcm_client_factory,
       const GCMClient::ChromeBuildInfo& chrome_build_info,
       const std::string& channel_status_request_url,
       const std::string& user_agent,
       PrefService* prefs,
       const base::FilePath& store_path,
       const scoped_refptr<net::URLRequestContextGetter>& request_context,
       const scoped_refptr<base::SequencedTaskRunner>& ui_thread,
@@ skipping 180 matching lines @@
 
   // Used to pass a weak pointer to the IO worker.
   base::WeakPtrFactory<GCMDriverDesktop> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GCMDriverDesktop);
 };
 
 }  // namespace gcm
 
 #endif  // COMPONENTS_GCM_DRIVER_GCM_DRIVER_DESKTOP_H_