Use the default dispatcher where possible for nested message loops.

ui/views/widget/desktop_aura/desktop_dispatcher_client.h

Index: ui/views/widget/desktop_aura/desktop_dispatcher_client.h
diff --git a/ui/views/widget/desktop_aura/desktop_dispatcher_client.h b/ui/views/widget/desktop_aura/desktop_dispatcher_client.h
index b59f4da2027779879bec7e87f6b29ababbcfc611..1af8f94e4fcabbc58553db1054ed8e52198587f6 100644
--- a/ui/views/widget/desktop_aura/desktop_dispatcher_client.h
+++ b/ui/views/widget/desktop_aura/desktop_dispatcher_client.h
@@ -6,6 +6,7 @@
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_DISPATCHER_CLIENT_H_
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "ui/aura/client/dispatcher_client.h"
 #include "ui/views/views_export.h"
 
@@ -20,8 +21,11 @@ class VIEWS_EXPORT DesktopDispatcherClient
 
   virtual void RunWithDispatcher(base::MessagePumpDispatcher* dispatcher,
                                  aura::Window* associated_window) OVERRIDE;
+  virtual void QuitNestedMessageLoop() OVERRIDE;
 
  private:
+  base::Closure quit_closure_;
+
   DISALLOW_COPY_AND_ASSIGN(DesktopDispatcherClient);
 };