Make `chrome` target build without unused data members on Linux.

components/gcm_driver/instance_id/instance_id_impl.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_IMPL_H_
 #define COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_IMPL_H_
 
 #include <map>
 #include <string>
 
@@ skipping 55 matching lines @@
       const GetTokenCallback& callback);
   void DoDeleteToken(const std::string& authorized_entity,
                      const std::string& scope,
                      const DeleteTokenCallback& callback);
   void DoDeleteID(const DeleteIDCallback& callback);
 
   gcm::GCMDriver* gcm_driver_;  // Not owned.
 
   gcm::GCMDelayedTaskController delayed_task_controller_;
 
-  // Flag to indicate that we have tries to load the data from the store.
-  bool load_from_store_;
-
   // The generated Instance ID.
   std::string id_;
 
   // The time when the Instance ID has been generated.
   base::Time creation_time_;
 
   base::WeakPtrFactory<InstanceIDImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InstanceIDImpl);
 };
 
 }  // namespace instance_id
 
 #endif  // COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_IMPL_H_