X11: Avoid round-tripping to get the cursor position

ui/events/platform/x11/x11_event_source.h

Index: ui/events/platform/x11/x11_event_source.h
diff --git a/ui/events/platform/x11/x11_event_source.h b/ui/events/platform/x11/x11_event_source.h
index cf4051517a0a5cd24c13a4643f1c7724fdf0c11b..0ff50da4cfad81b96ba51bf68638e74dfc1781dd 100644
--- a/ui/events/platform/x11/x11_event_source.h
+++ b/ui/events/platform/x11/x11_event_source.h
@@ -77,6 +77,10 @@ class EVENTS_EXPORT X11EventSource {
   // current event does not have a timestamp.
   Time GetTimestamp();
 
+  // If an event is being dispatched, copies the event into *|event| and
+  // returns true.  Otherwise *|event| is untouched and this returns false.
+  const XEvent* get_dispatching_event() const { return dispatching_event_; }

[sadrul, 2016/10/07 02:12:51]

Exposing the raw XEvent feels more icky. I would prefer something like 'bool
GetRootCursorLocationFromCurrentEvent(gfx::Point* location)' or something like
that.

[Tom (Use chromium acct), 2016/10/07 21:13:18]

Done.

+
   void StopCurrentEventStream();
   void OnDispatcherListChanged();
 
@@ -108,6 +112,9 @@ class EVENTS_EXPORT X11EventSource {
   // The timestamp of the event being dispatched.
   Time event_timestamp_;
 
+  // The event being dispatched, or nullptr if there is none.
+  XEvent* dispatching_event_;
+
   // State necessary for UpdateLastSeenServerTime
   bool dummy_initialized_;
   XWindow dummy_window_;