Implement InstanceIDAndroid using InstanceIDWithSubtype.java

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 <string>
 
@@ skipping 39 matching lines @@
   typedef base::Callback<void(const std::string& token,
                               Result result)> GetTokenCallback;
   typedef base::Callback<void(Result result)> DeleteTokenCallback;
   typedef base::Callback<void(Result result)> DeleteIDCallback;
 
   static const int kInstanceIDByteLength = 8;
 
   // Creator.
   // |app_id|: identifies the application that uses the Instance ID.
   // |handler|: provides the GCM functionality needed to support Instance ID.
-  //            Must outlive this class.
+  //            Must outlive this class. On Android, this can be null instead.

[jianli, 2016/04/08 23:20:00]

Probably it is better to refactor this in order to avoid having different value
for a parameter. I am thinking:
  ... Create(const std::string& app_id, gcm::GCMDriver* gcm_driver)

InstanceIDAndroid could ignore gcm_driver parameter while InstanceIDImpl could
get InstanceIDHandler out of it.

[johnme, 2016/04/13 11:42:12]

Hmm, Peter suggested we pass in only the InstanceIDHandler in
https://codereview.chromium.org/1785613006, to insulate InstanceID from the
implementation detail that InstanceIDHandler happens to be obtained from &
implemented by GCMDriver (which is a different component). That still seems a
good reason.

This patch doesn't change this behaviour anyway (it was already null on Android,
I'm just documenting that fact).

   static scoped_ptr<InstanceID> Create(const std::string& app_id,
                                        gcm::InstanceIDHandler* handler);
 
   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.
@@ skipping 28 matching lines @@
                            const DeleteTokenCallback& callback) = 0;
 
   // Resets the app instance identifier and revokes all tokens associated with
   // it.
   // |callback|: to be called once the asynchronous operation is done.
   virtual void DeleteID(const DeleteIDCallback& callback) = 0;
 
   std::string app_id() const { return app_id_; }
 
  protected:
-  InstanceID(const std::string& app_id, gcm::InstanceIDHandler* handler);
+  InstanceID(const std::string& app_id);
 
   void NotifyTokenRefresh(bool update_id);
 
-  gcm::InstanceIDHandler* handler() const { return handler_; }
-
  private:
-  // Owned by GCMProfileServiceFactory, which is a dependency of
-  // InstanceIDProfileServiceFactory, which owns this.
-  gcm::InstanceIDHandler* handler_;
-
   std::string app_id_;
   TokenRefreshCallback token_refresh_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(InstanceID);
 };
 
 }  // namespace instance_id
 
 #endif  // COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_H_