Make event-targeting asynchronous in window server.

services/ui/ws/event_dispatcher_delegate.h

Index: services/ui/ws/event_dispatcher_delegate.h
diff --git a/services/ui/ws/event_dispatcher_delegate.h b/services/ui/ws/event_dispatcher_delegate.h
index 28a2a0a123f12e8aeb0dc4ba1796517bb9833715..485826f35f078d31a6867f3d59204e05cd3e2075 100644
--- a/services/ui/ws/event_dispatcher_delegate.h
+++ b/services/ui/ws/event_dispatcher_delegate.h
@@ -67,6 +67,9 @@ class EventDispatcherDelegate {
                                           const ui::Event& event,
                                           Accelerator* accelerator) = 0;
 
+  // Starts processing the next event in the event queue.
+  virtual void ProcessNextEventFromQueue() = 0;
+
   // Returns the id of the client to send events to. |in_nonclient_area| is
   // true if the event occurred in the non-client area of the window.
   virtual ClientSpecificId GetEventTargetClientId(const ServerWindow* window,