cros: Maybe fix recent failures on trunk.

content/test/test_renderer_host.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 "content/test/test_renderer_host.h"
 
 #include "content/browser/renderer_host/render_view_host_factory.h"
 #include "content/browser/renderer_host/test_render_view_host.h"
 #include "content/browser/site_instance_impl.h"
 #include "content/browser/web_contents/navigation_entry_impl.h"
@@ skipping 130 matching lines @@
       new aura::test::TestStackingClient(root_window_.get()));
 #endif  // USE_AURA
   SetContents(CreateTestWebContents());
 }
 
 void RenderViewHostTestHarness::TearDown() {
   SetContents(NULL);
 #if defined(USE_AURA)
   test_stacking_client_.reset();
   root_window_.reset();
+  aura::Env::DeleteInstance();
 #endif
 
   // Make sure that we flush any messages related to WebContentsImpl destruction
   // before we destroy the browser context.
   MessageLoop::current()->RunAllPending();
 
   // Release the browser context on the UI thread.
   message_loop_.DeleteSoon(FROM_HERE, browser_context_.release());
   message_loop_.RunAllPending();
 }
 
 void RenderViewHostTestHarness::SetRenderProcessHostFactory(
     RenderProcessHostFactory* factory) {
     rvh_test_enabler_.rvh_factory_->set_render_process_host_factory(factory);
 }
 
 }  // namespace content