Implement scaling detection in WindowCapturerWin

WindowCapturerWin wrongly calculate the image size if the application it target
does not support high DPI. It causes part of the output frame black. See bug for
details.

Bug: webrtc:8112
Change-Id: I33c66dfa977ec08a29c56ff86ae37320b1459c87
Reviewed-on: https://chromium-review.googlesource.com/634383
Commit-Queue: Zijie He <zijiehe@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#19531}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: af5686a229eb16a68771d7bad204e7aea8d89958
6 files changed