Add support for GCM subtypes to desktop Instance ID implementation

components/gcm_driver/instance_id/instance_id.h

 // Copyright 2015 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_INSTANCE_ID_INSTANCE_ID_H_
 #define COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 42 matching lines @@
       GetCreationTimeCallback;
   typedef base::Callback<void(const std::string& token,
                               Result result)> GetTokenCallback;
   typedef base::Callback<void(const std::string&, const std::string&)>
       GetEncryptionInfoCallback;
   typedef base::Callback<void(Result result)> DeleteTokenCallback;
   typedef base::Callback<void(Result result)> DeleteIDCallback;
 
   static const int kInstanceIDByteLength = 8;
 
-  // Creator.
+  // Creator. Should only be used by InstanceIDDriver::GetInstanceID.
   // |app_id|: identifies the application that uses the Instance ID.
   // |handler|: provides the GCM functionality needed to support Instance ID.
   //            Must outlive this class. On Android, this can be null instead.
-  static std::unique_ptr<InstanceID> Create(const std::string& app_id,
-                                            gcm::GCMDriver* gcm_driver);
+  static std::unique_ptr<InstanceID> CreateInternal(const std::string& app_id,
+                                                    gcm::GCMDriver* gcm_driver);
 
   virtual ~InstanceID();
 
   // Sets the callback that will be invoked when the token refresh event needs
   // to be triggered.
   void SetTokenRefreshCallback(const TokenRefreshCallback& callback);
 
   // Returns the Instance ID.
   virtual void GetID(const GetIDCallback& callback) = 0;
 
@@ skipping 65 matching lines @@
   TokenRefreshCallback token_refresh_callback_;
 
   base::WeakPtrFactory<InstanceID> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InstanceID);
 };
 
 }  // namespace instance_id
 
 #endif  // COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_H_