diff --git a/base/message_loop/message_loop.h b/base/message_loop/message_loop.h
index f4ed5a1..04709e6 100644
--- a/base/message_loop/message_loop.h
+++ b/base/message_loop/message_loop.h
@@ -96,11 +96,11 @@
 class BASE_EXPORT MessageLoop : public MessagePump::Delegate {
  public:
 
-#if defined(USE_GTK_MESSAGE_PUMP)
-  typedef MessagePumpGdkObserver Observer;
-#elif !defined(OS_MACOSX) && !defined(OS_ANDROID)
+#if defined(USE_AURA)
   typedef MessagePumpDispatcher Dispatcher;
   typedef MessagePumpObserver Observer;
+#elif defined(USE_GTK_MESSAGE_PUMP)
+  typedef MessagePumpGdkObserver Observer;
 #endif
 
   // A MessageLoop has a particular type, which indicates the set of