Work in progress: Adds MessagePumpDispatcher::ShouldExit(). This is used to handle the

ash/accelerators/accelerator_dispatcher.h

Index: ash/accelerators/accelerator_dispatcher.h
diff --git a/ash/accelerators/accelerator_dispatcher.h b/ash/accelerators/accelerator_dispatcher.h
index fcc69f0e61fcb113c4efe722514df7e066f2a402..adc719745f53a0148318d692dd739e55c9a82707 100644
--- a/ash/accelerators/accelerator_dispatcher.h
+++ b/ash/accelerators/accelerator_dispatcher.h
@@ -28,6 +28,7 @@ class ASH_EXPORT AcceleratorDispatcher : public MessageLoop::Dispatcher,
 
   // MessageLoop::Dispatcher overrides:
   virtual bool Dispatch(const base::NativeEvent& event) OVERRIDE;
+  virtual bool ShouldExit() OVERRIDE;
 
   // aura::WindowObserver overrides:
   virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;