Remove #pragma once from sync

sync/sessions/session_state.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.
 
 // The 'sessions' namespace comprises all the pieces of state that are
 // combined to form a SyncSession instance. In that way, it can be thought of
 // as an extension of the SyncSession type itself. Session scoping gives
 // context to things like "conflict progress", "update progress", etc, and the
 // separation this file provides allows clients to only include the parts they
 // need rather than the entire session stack.
 
 #ifndef SYNC_SESSIONS_SESSION_STATE_H_
 #define SYNC_SESSIONS_SESSION_STATE_H_
-#pragma once
 
 #include <set>
 #include <vector>
 
 #include "sync/engine/syncer_types.h"
 #include "sync/engine/syncproto.h"
 #include "sync/syncable/syncable_id.h"
 
 namespace syncer {
 namespace sessions {
@@ skipping 100 matching lines @@
   ~PerModelSafeGroupState();
 
   UpdateProgress update_progress;
   ConflictProgress conflict_progress;
 };
 
 }  // namespace sessions
 }  // namespace syncer
 
 #endif  // SYNC_SESSIONS_SESSION_STATE_H_