Use the default dispatcher where possible for nested message loops.

ash/accelerators/nested_dispatcher_controller.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 "ash/accelerators/nested_dispatcher_controller.h"
 
 #include "ash/accelerators/accelerator_dispatcher.h"
 #include "ash/shell.h"
+#include "base/auto_reset.h"
 #include "base/run_loop.h"
 
 namespace ash {
 
 NestedDispatcherController::NestedDispatcherController() {
 }
 
 NestedDispatcherController::~NestedDispatcherController() {
 }
 
 void NestedDispatcherController::RunWithDispatcher(
     base::MessagePumpDispatcher* nested_dispatcher,
     aura::Window* associated_window) {
   base::MessageLoopForUI* loop = base::MessageLoopForUI::current();
   base::MessageLoopForUI::ScopedNestableTaskAllower allow_nested(loop);
 
   AcceleratorDispatcher dispatcher(nested_dispatcher, associated_window);
 
   // TODO(jbates) crbug.com/134753 Find quitters of this RunLoop and have them
   //              use run_loop.QuitClosure().
   base::RunLoop run_loop(&dispatcher);
+  base::AutoReset<base::Closure> reset_closure(&quit_closure_,
+                                               run_loop.QuitClosure());
   run_loop.Run();
 }
 
+void NestedDispatcherController::QuitNestedMessageLoop() {
+  CHECK(!quit_closure_.is_null());
+  quit_closure_.Run();
+}
+
 }  // namespace ash