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

sync/syncable/syncable_columns.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_SYNCABLE_COLUMNS_H_
 #define SYNC_SYNCABLE_SYNCABLE_COLUMNS_H_
 #pragma once
 
 #include "sync/syncable/entry_kernel.h"
 #include "sync/syncable/syncable_changes_version.h"
 
+namespace syncer {
 namespace syncable {
 
 struct ColumnSpec {
   const char* name;
   const char* spec;
 };
 
 // Must be in exact same order as fields in syncable.
 static const ColumnSpec g_metas_columns[] = {
   //////////////////////////////////////
@@ skipping 41 matching lines @@
 // At least enforce that there are equal number of column names and fields.
 COMPILE_ASSERT(arraysize(g_metas_columns) >= FIELD_COUNT, missing_column_name);
 COMPILE_ASSERT(arraysize(g_metas_columns) <= FIELD_COUNT, extra_column_names);
 
 static inline const char* ColumnName(int field) {
   DCHECK(field < BEGIN_TEMPS);
   return g_metas_columns[field].name;
 }
 
 }  // namespace syncable
+}  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_SYNCABLE_COLUMNS_H_