Remove #pragma once from sync

sync/internal_api/public/http_post_provider_interface.h

 // 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.
 
 #ifndef SYNC_INTERNAL_API_PUBLIC_HTTP_POST_PROVIDER_INTERFACE_H_
 #define SYNC_INTERNAL_API_PUBLIC_HTTP_POST_PROVIDER_INTERFACE_H_
-#pragma once
 
 #include <string>
 
 namespace syncer {
 
 // An interface the embedding application (e.g. Chromium) implements to provide
 // required HTTP POST functionality to the syncer backend. This interface is
 // designed for one-time use. You create one, use it, and create another if you
 // want to make a subsequent POST.
 class HttpPostProviderInterface {
@@ skipping 36 matching lines @@
   // This must be safe to call from any thread.
   virtual void Abort() = 0;
 
  protected:
   virtual ~HttpPostProviderInterface() {}
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_HTTP_POST_PROVIDER_INTERFACE_H_