Run event executor on the ui thread to remove the need to explicitly XFlush() the XTest calls.

remoting/host/event_executor_mac.h

Index: remoting/host/event_executor_mac.h
diff --git a/remoting/host/event_executor_mac.h b/remoting/host/event_executor_mac.h
index 758ccc04389887658534c9535e95bdc30b020179..66288a0b3cada8d2e9ad70652db64bc716cfd872 100644
--- a/remoting/host/event_executor_mac.h
+++ b/remoting/host/event_executor_mac.h
@@ -16,14 +16,14 @@ namespace remoting {
 // A class to generate events on Mac.
 class EventExecutorMac : public protocol::InputStub {
  public:
-  EventExecutorMac(MessageLoop* message_loop, Capturer* capturer);
+  EventExecutorMac(MessageLoopForUI* message_loop, Capturer* capturer);
   virtual ~EventExecutorMac();
 
   virtual void InjectKeyEvent(const protocol::KeyEvent* event, Task* done);
   virtual void InjectMouseEvent(const protocol::MouseEvent* event, Task* done);
 
  private:
-  MessageLoop* message_loop_;
+  MessageLoopForUI* message_loop_;
   Capturer* capturer_;
 
   DISALLOW_COPY_AND_ASSIGN(EventExecutorMac);