Convert //chrome/browser/sync_file_system from scoped_ptr to std::unique_ptr

chrome/browser/sync_file_system/drive_backend/callback_tracker.cc

 // 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.
 
 #include "chrome/browser/sync_file_system/drive_backend/callback_tracker.h"
 
 #include <algorithm>
 
 namespace sync_file_system {
 namespace drive_backend {
 
 CallbackTracker::CallbackTracker() {
 }
 
 CallbackTracker::~CallbackTracker() {
   AbortAll();
 }
 
 void CallbackTracker::AbortAll() {
   AbortClosureByHelper helpers;
   std::swap(helpers, helpers_);
   for (AbortClosureByHelper::iterator itr = helpers.begin();
        itr != helpers.end(); ++itr) {
     delete itr->first;
     itr->second.Run();
   }
 }
 
-scoped_ptr<internal::AbortHelper> CallbackTracker::PassAbortHelper(
+std::unique_ptr<internal::AbortHelper> CallbackTracker::PassAbortHelper(
     internal::AbortHelper* helper) {
   if (helpers_.erase(helper) == 1)
-    return scoped_ptr<internal::AbortHelper>(helper);
+    return std::unique_ptr<internal::AbortHelper>(helper);
   return nullptr;
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system