Remove #pragma once from sync

sync/sessions/sync_session.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.
 
 // A class representing an attempt to synchronize the local syncable data
 // store with a sync server. A SyncSession instance is passed as a stateful
 // bundle to and from various SyncerCommands with the goal of converging the
 // client view of data with that of the server. The commands twiddle with
 // session status in response to events and hiccups along the way, set and
 // query session progress with regards to conflict resolution and applying
 // server updates, and access the SyncSessionContext for the current session
 // via SyncSession instances.
 
 #ifndef SYNC_SESSIONS_SYNC_SESSION_H_
 #define SYNC_SESSIONS_SYNC_SESSION_H_
-#pragma once
 
 #include <map>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
@@ skipping 216 matching lines @@
 
  private:
   SyncSession* session_;
   DISALLOW_COPY_AND_ASSIGN(ScopedSetSessionWriteTransaction);
 };
 
 }  // namespace sessions
 }  // namespace syncer
 
 #endif  // SYNC_SESSIONS_SYNC_SESSION_H_