aura-x11: Install the dispatcher as a message-pump observer.

ui/aura/dispatcher_linux.h

Index: ui/aura/dispatcher_linux.h
diff --git a/ui/aura/dispatcher_linux.h b/ui/aura/dispatcher_linux.h
index 56255585900b70e4d0f6f81a72844363d73ff6a8..c18cc3073c19f29624868d4a55b09146b1849529 100644
--- a/ui/aura/dispatcher_linux.h
+++ b/ui/aura/dispatcher_linux.h
@@ -17,7 +17,8 @@
 
 namespace aura {
 
-class DispatcherLinux : public MessageLoop::Dispatcher {
+class DispatcherLinux : public MessageLoop::Dispatcher,
+                        public base::MessagePumpObserver {
  public:
   DispatcherLinux();
   virtual ~DispatcherLinux();
@@ -29,6 +30,11 @@ class DispatcherLinux : public MessageLoop::Dispatcher {
   // Overridden from MessageLoop::Dispatcher:
   virtual bool Dispatch(const base::NativeEvent& event) OVERRIDE;
 
+  // Overridden from base::MessagePumpObserver:
+  virtual base::EventStatus WillProcessEvent(
+      const base::NativeEvent& event) OVERRIDE;
+  virtual void DidProcessEvent(const base::NativeEvent& event) OVERRIDE;
+
  private:
   typedef std::map< ::Window, MessageLoop::Dispatcher* > DispatchersMap;