Remove the singleton instance get/delete methods from RootWindow (yay)

chrome/test/base/chrome_render_view_host_test_harness.cc

 // Copyright (c) 2011 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 "chrome/test/base/chrome_render_view_host_test_harness.h"
 
 #include "chrome/test/base/testing_profile.h"
 
 #if defined(USE_AURA)
 #include "ash/shell.h"
@@ skipping 15 matching lines @@
 void ChromeRenderViewHostTestHarness::SetUp() {
   if (!browser_context_.get())
     browser_context_.reset(new TestingProfile());
   RenderViewHostTestHarness::SetUp();
 }
 
 void ChromeRenderViewHostTestHarness::TearDown() {
   RenderViewHostTestHarness::TearDown();
 #if defined(USE_AURA)
   ash::Shell::DeleteInstance();
-  aura::RootWindow::DeleteInstance();
   aura::Env::DeleteInstance();
 #endif
 }