ui: Use base::MessageLoop.

ui/aura/env.h

Index: ui/aura/env.h
diff --git a/ui/aura/env.h b/ui/aura/env.h
index 6a0a83e702d648a50a89a9c623d49be933ca5b4c..99b05773e48bbe6c050eb837dcba72bb18598b9b 100644
--- a/ui/aura/env.h
+++ b/ui/aura/env.h
@@ -67,7 +67,7 @@ class AURA_EXPORT Env : public ui::EventTarget {
   // base::RunLoop(dispatcher), or used to dispatch an event by
   // |Dispatch(const NativeEvent&)| on it. It must never be stored.
 #if !defined(OS_MACOSX)
-  MessageLoop::Dispatcher* GetDispatcher();
+  base::MessageLoop::Dispatcher* GetDispatcher();
 #endif
 
   // Invoked by RootWindow when its host is activated.
@@ -91,7 +91,7 @@ class AURA_EXPORT Env : public ui::EventTarget {
 
   ObserverList<EnvObserver> observers_;
 #if !defined(USE_X11)
-  scoped_ptr<MessageLoop::Dispatcher> dispatcher_;
+  scoped_ptr<base::MessageLoop::Dispatcher> dispatcher_;
 #endif
 
   static Env* instance_;