[Sync] Fix namespaces for the browser_sync component.

components/browser_sync/profile_sync_service_mock.cc

 // 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.
 
 #include "components/browser_sync/profile_sync_service_mock.h"
 
 #include <utility>
 
+namespace browser_sync {
+
 ProfileSyncServiceMock::ProfileSyncServiceMock(InitParams init_params)
     : ProfileSyncService(std::move(init_params)) {
   ON_CALL(*this, IsSyncRequested()).WillByDefault(testing::Return(true));
 }
 
 ProfileSyncServiceMock::ProfileSyncServiceMock(InitParams* init_params)
     : ProfileSyncServiceMock(std::move(*init_params)) {}
 
 ProfileSyncServiceMock::~ProfileSyncServiceMock() {}
+
+}  // namespace browser_sync