Make GCMDriver::GetInstanceIDHandler protected, to avoid misuse

components/gcm_driver/instance_id/instance_id.h

Index: components/gcm_driver/instance_id/instance_id.h
diff --git a/components/gcm_driver/instance_id/instance_id.h b/components/gcm_driver/instance_id/instance_id.h
index 9adf0e5def2604150b45e9a3f99fdbe5614cc9ee..62286314359ddd5b97077ea6d643d2d1e55917f1 100644
--- a/components/gcm_driver/instance_id/instance_id.h
+++ b/components/gcm_driver/instance_id/instance_id.h
@@ -15,6 +15,7 @@
 
 namespace gcm {
 class GCMDriver;
+class InstanceIDHandler;
 }  // namespace gcm
 
 namespace instance_id {
@@ -57,7 +58,7 @@ class InstanceID {
   // Creator.
   // |app_id|: identifies the application that uses the Instance ID.
   // |gcm_driver|: driver to access the GCM functionalities needed to support
-  //               Instance ID.
+  //               Instance ID. Its InstanceIDHandler must outlive this class.
   static scoped_ptr<InstanceID> Create(const std::string& app_id,
                                        gcm::GCMDriver* gcm_driver);
 
@@ -106,10 +107,12 @@ class InstanceID {
   std::string app_id() const { return app_id_; }
 
  protected:
-  explicit InstanceID(const std::string& app_id);
+  InstanceID(const std::string& app_id, gcm::GCMDriver* gcm_driver);

[Peter Beverloo, 2016/03/10 21:11:23]

As discussed, let's limit knowledge and have this be the gcm::InstanceIDHandler.

[johnme, 2016/03/11 15:56:04]

Done.

 
   void NotifyTokenRefresh(bool update_id);
 
+  gcm::InstanceIDHandler* handler_;  // Not owned.

[Peter Beverloo, 2016/03/10 21:11:23]

Per the styleguide:

""Limit the use of protected to those member functions that might need to be
accessed from subclasses. Note that data members should be private.""

[johnme, 2016/03/11 15:56:04]

Done.

+
  private:
   std::string app_id_;
   TokenRefreshCallback token_refresh_callback_;