WindowUnderPoint() is a platform independent function to return the id of the
first window in z-order under a certain DesktopVector. It equals to
GetAncestor(WindowFromPoint(point), GA_ROOT)
on Windows.
This CL includes the change to Windows / Mac OSX only to control the size in a
reasonable range. Implementation for Linux will be added in a coming change.
Bug: webrtc:7950
Change-Id: I57e423294fc8aeaa12d05cb626a1912240b2d4d0
Reviewed-on: https://chromium-review.googlesource.com/595022
Commit-Queue: Zijie He <zijiehe@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#19263}