This change ensures DirectX capturer to return the same ScreenId as GDI capturer
for each monitor. So MouseCursoeMonitor can work correctly with the DirectX
capturer.
This is a temporary fix of webrtc:7950.
Bug: webrtc:7950
Change-Id: Icd3f40556701811c21c773a39260a74db43979f3
Reviewed-on: https://chromium-review.googlesource.com/571101
Commit-Queue: Zijie He <zijiehe@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#19079}