Disable screen capturer tests on Windows

Windows cannot capture contents on VMs hosted in GCE, disable them to unblock
GCE hosting.

Bug: webrtc:8153
Change-Id: Iacdce15008cc092dce36d08b1d5565bbaa5def1f
Reviewed-on: https://chromium-review.googlesource.com/634083
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Commit-Queue: Zijie He <zijiehe@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#19502}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 0cab085157fb55f1b61e6700fe636895d9164e9a
1 file changed