aura: Require explicit ownership of the Env instance.

ui/views_content_client/views_content_client_main_parts_aura.cc

 // Copyright 2014 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 "ui/views_content_client/views_content_client_main_parts_aura.h"
 
-#include "ui/aura/env.h"
 #include "ui/wm/core/wm_state.h"
 
 namespace ui {
 
 ViewsContentClientMainPartsAura::ViewsContentClientMainPartsAura(
     const content::MainFunctionParams& content_params,
     ViewsContentClient* views_content_client)
     : ViewsContentClientMainParts(content_params, views_content_client) {
 }
 
 ViewsContentClientMainPartsAura::~ViewsContentClientMainPartsAura() {
 }
 
 void ViewsContentClientMainPartsAura::ToolkitInitialized() {
   ViewsContentClientMainParts::ToolkitInitialized();
 
   wm_state_.reset(new ::wm::WMState);
 }
 
 void ViewsContentClientMainPartsAura::PostMainMessageLoopRun() {
-  aura::Env::DeleteInstance();
-
   ViewsContentClientMainParts::PostMainMessageLoopRun();
 }
 
 }  // namespace ui