ozone: Fix ScreenOzone::GetWindowAtScreenPoint

Screen::GetWindowAtScreenPoint function is supposed to
return the NativeWindow under a given screen point.
The current ScreenOzone implementation, unlike ScreenAsh,
returns the root window instead of the exact
window corresponding the that point inside the window
hierarchy.

This CL fixes that insconsistency, applying a solution similar
to the one used in ScreenAsh: it relies on ScreenPositionClient
and aura::Window::GetEventHandlerForPoint to get the correct
window within window hierarchy under the specified point.

Bug: 578890
Change-Id: If3b078fb933006f323425bbcd05d9ccb504b8b61
Reviewed-on: https://chromium-review.googlesource.com/c/1477828
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Nick Diego Yamane <nickdiego@igalia.com>
Cr-Commit-Position: refs/heads/master@{#633920}
1 file changed