Make tapDown async.

content/browser/renderer_host/input/immediate_input_router.h

Index: content/browser/renderer_host/input/immediate_input_router.h
diff --git a/content/browser/renderer_host/input/immediate_input_router.h b/content/browser/renderer_host/input/immediate_input_router.h
index 1d1a0c0e168d3eb8814a1809b3e4575ea72f0504..d453ed96a0e6bdbbfbe7e517d5f3b4b00ebe26c6 100644
--- a/content/browser/renderer_host/input/immediate_input_router.h
+++ b/content/browser/renderer_host/input/immediate_input_router.h
@@ -123,7 +123,8 @@ private:
   // Called by ProcessInputEventAck() to process a gesture event ack message.
   // This validates the gesture for suppression of touchpad taps and sends one
   // previously queued coalesced gesture if it exists.
-  void ProcessGestureAck(int type, InputEventAckState ack_result);
+  void ProcessGestureAck(WebKit::WebInputEvent::Type,
+                         InputEventAckState ack_result);
 
   // Called on ProcessInputEventAck() to process a touch event ack message.
   // This can result in a gesture event being generated and sent back to the