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..fb69a11ef7776187fd5b9695521b8d55a355c3ea 100644
--- a/components/gcm_driver/instance_id/instance_id.h
+++ b/components/gcm_driver/instance_id/instance_id.h
@@ -14,7 +14,7 @@
 #include "base/time/time.h"
 
 namespace gcm {
-class GCMDriver;
+class InstanceIDHandler;
 }  // namespace gcm
 
 namespace instance_id {
@@ -56,10 +56,10 @@ 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.
+  // |handler|: provides the GCM functionality needed to support Instance ID.
+  //            Must outlive this class.
   static scoped_ptr<InstanceID> Create(const std::string& app_id,
-                                       gcm::GCMDriver* gcm_driver);
+                                       gcm::InstanceIDHandler* handler);
 
   virtual ~InstanceID();
 
@@ -106,11 +106,17 @@ 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::InstanceIDHandler* handler);
 
   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_;