[Sync] Move sync/{internal_api,syncable} into syncer namespace

sync/syncable/entry.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_SYNCABLE_ENTRY_H_
 #define SYNC_SYNCABLE_ENTRY_H_
 #pragma once
 
 #include "sync/syncable/entry_kernel.h"
 
 namespace syncer {
 class ReadNode;
-}
 
 namespace syncable {
 
 class Directory;
 class BaseTransaction;
 
 // A read-only meta entry
 // Instead of:
 //   Entry e = transaction.GetById(id);
 // use:
@@ skipping 119 matching lines @@
   friend class Directory;
   friend class syncer::ReadNode;
   friend std::ostream& operator << (std::ostream& s, const Entry& e);
 
   DISALLOW_COPY_AND_ASSIGN(Entry);
 };
 
 std::ostream& operator<<(std::ostream& os, const Entry& entry);
 
 }  // namespace syncable
+}  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_ENTRY_H_