[Sync] Removing duplicated includes between cc and h files.

components/sync/core_impl/js_mutation_event_observer.cc

 // Copyright (c) 2012 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 "components/sync/core_impl/js_mutation_event_observer.h"
 
 #include <stddef.h>
-#include <stdint.h>
-
-#include <string>
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/values.h"
 #include "components/sync/js/js_event_details.h"
 #include "components/sync/js/js_event_handler.h"
 
 namespace syncer {
 
@@ skipping 80 matching lines @@
     const std::string& name,
     const JsEventDetails& details) {
   if (!event_handler_.IsInitialized()) {
     NOTREACHED();
     return;
   }
   event_handler_.Call(from_here, &JsEventHandler::HandleJsEvent, name, details);
 }
 
 }  // namespace syncer