Find display root ServerWindow for located events in mus.

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 cb4ce101f33e2e9e094839da3981b9eca9c4129c..82a5216064a72957bd81a10924021c0fadb48539 100644
--- a/services/ui/ws/event_dispatcher_delegate.h
+++ b/services/ui/ws/event_dispatcher_delegate.h
@@ -66,8 +66,10 @@ class EventDispatcherDelegate {
                                                   bool in_nonclient_area) = 0;
 
   // Returns the window to start searching from at the specified location, or
-  // null if there is a no window containing |location|.
-  virtual ServerWindow* GetRootWindowContaining(const gfx::Point& location) = 0;
+  // null if there is a no window containing |location|. |location| should be in
+  // screen coordinates and if a window is returned then |location| will be
+  // updated to be relative to the origin of the window.
+  virtual ServerWindow* GetRootWindowContaining(gfx::Point* location) = 0;
 
   // Called when event dispatch could not find a target. OnAccelerator may still
   // be called.