Disallow redundant Bind calls.

chrome/browser/sync_file_system/drive_backend/callback_helper.h

 // Copyright 2014 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 CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_HELPER_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_HELPER_H_
 
 #include <memory>
 #include <type_traits>
 
@@ skipping 48 matching lines @@
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
   const tracked_objects::Location from_here_;
   std::unique_ptr<base::Callback<T>> callback_;
 
   DISALLOW_COPY_AND_ASSIGN(CallbackHolder);
 };
 
 template <typename>
 struct RelayToTaskRunnerHelper;
 
+template <>
+struct RelayToTaskRunnerHelper<void()> {
+  static void Run(CallbackHolder<void()>* holder) {
+    holder->task_runner()->PostTask(holder->from_here(), holder->callback());
+  }
+};
+
 template <typename... Args>
 struct RelayToTaskRunnerHelper<void(Args...)> {
   static void Run(CallbackHolder<void(Args...)>* holder, Args... args) {
     holder->task_runner()->PostTask(
         holder->from_here(),
         base::Bind(holder->callback(), RebindForward(args)...));
   }
 };
 
 }  // namespace internal
@@ skipping 19 matching lines @@
     const base::Callback<T>& callback) {
   return RelayCallbackToTaskRunner(
       base::ThreadTaskRunnerHandle::Get(),
       from_here, callback);
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_HELPER_H_