Make GCMDriver::GetInstanceIDHandler protected, to avoid misuse

components/gcm_driver/fake_gcm_driver.cc

 // 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.
 
 #include "components/gcm_driver/fake_gcm_driver.h"
 
 #include "base/files/file_path.h"
 
 namespace gcm {
 
@@ skipping 82 matching lines @@
 base::Time FakeGCMDriver::GetLastTokenFetchTime() {
   return base::Time();
 }
 
 void FakeGCMDriver::SetLastTokenFetchTime(const base::Time& time) {
 }
 
 void FakeGCMDriver::WakeFromSuspendForHeartbeat(bool wake) {
 }
 
-InstanceIDHandler* FakeGCMDriver::GetInstanceIDHandler() {
+InstanceIDHandler* FakeGCMDriver::GetInstanceIDHandlerInternal() {
   return NULL;
 }
 
 void FakeGCMDriver::AddHeartbeatInterval(const std::string& scope,
                                          int interval_ms) {
 }
 
 void FakeGCMDriver::RemoveHeartbeatInterval(const std::string& scope) {
 }
 
 }  // namespace gcm