[cros] Treat windows as visible while they are being captured.

On CrOS, a window can be occluded by another window, causing content running
in full-occluded windows not be rendered.  Windows that are being
captured (e.g. for screen-sharing) should continue to render even
when fully-occluded.

Bug: 935971
Test: covered by unittests
Change-Id: Ib3098f2a85aa0bb3924924732d22b7c51d125c60
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1540101
Reviewed-by: Yuri Wiitala <miu@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#646671}
2 files changed