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

ash/test/ash_test_base.cc

Index: ash/test/ash_test_base.cc
===================================================================
--- ash/test/ash_test_base.cc	(revision 124527)
+++ ash/test/ash_test_base.cc	(working copy)
@@ -13,18 +13,12 @@
 namespace test {
 
 AshTestBase::AshTestBase() {
-  helper_.InitRootWindow(Shell::GetRootWindow());
 }
 
 AshTestBase::~AshTestBase() {
-  // 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.
-  aura::RootWindow::DeleteInstance();
 }
 
 void AshTestBase::SetUp() {
-  helper_.SetUp();
-
   // Creates Shell and hook with Desktop.
   TestShellDelegate* delegate = new TestShellDelegate;
   Shell::WindowMode window_mode = Shell::MODE_OVERLAPPING;
@@ -32,6 +26,9 @@
     delegate->SetOverrideWindowMode(window_mode);
   ash::Shell::CreateInstance(delegate);
 
+  helper_.SetUp();
+  helper_.InitRootWindow(Shell::GetRootWindow());
+
   // Disable animations during tests.
   ui::LayerAnimator::set_disable_animations_for_test(true);
 }
@@ -40,10 +37,10 @@
   // Flush the message loop to finish pending release tasks.
   RunAllPendingInMessageLoop();
 
+  helper_.TearDown();
+
   // Tear down the shell.
   Shell::DeleteInstance();
-
-  helper_.TearDown();
 }
 
 bool AshTestBase::GetOverrideWindowMode(Shell::WindowMode* window_mode) {