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

ui/aura/test/aura_test_base.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 "ui/aura/test/aura_test_base.h"
 
 #include "ui/aura/root_window.h"
 #include "ui/aura/test/test_stacking_client.h"
 
 namespace aura {
 namespace test {
 
-AuraTestBase::AuraTestBase() : root_window_(RootWindow::GetInstance()) {
-  helper_.InitRootWindow(root_window_);
+AuraTestBase::AuraTestBase() {
 }
 
 AuraTestBase::~AuraTestBase() {
-  // Flush the message loop because we have pending release tasks
-  // and these tasks if un-executed would upset Valgrind.
-  helper_.RunAllPendingInMessageLoop(root_window_);
-
-  // Ensure that we don't use the previously-allocated static RootWindow object
-  // later -- on Linux, it holds a reference to our message loop's X connection.
-  RootWindow::DeleteInstance();
 }
 
 void AuraTestBase::SetUp() {
   testing::Test::SetUp();
+  root_window_.reset(new aura::RootWindow);
+  helper_.InitRootWindow(root_window());
   helper_.SetUp();
   stacking_client_.reset(new TestStackingClient(root_window()));
 }
 
 void AuraTestBase::TearDown() {
+  // Flush the message loop because we have pending release tasks
+  // and these tasks if un-executed would upset Valgrind.
+  RunAllPendingInMessageLoop();
+
   stacking_client_.reset();
   helper_.TearDown();
+  root_window_.reset();
   testing::Test::TearDown();
 }
 
 void AuraTestBase::RunAllPendingInMessageLoop() {
-  helper_.RunAllPendingInMessageLoop(root_window_);
+  helper_.RunAllPendingInMessageLoop(root_window());
 }
 
 }  // namespace test
 }  // namespace aura