Send occlusion fraction to Wayland clients.

  is sent to the Android side.

Bug: b/112668686
Bug: b/110011377
Test: Occlusion fraction changes upon remote surface losing focus and
Change-Id: Id622509a1eb504db945eb7c0b6c6db5256103d4d
Reviewed-on: https://chromium-review.googlesource.com/c/1179560
Commit-Queue: Eliot Courtney <edcourtney@chromium.org>
Reviewed-by: Mitsuru Oshima (gardener - slow) <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616923}
9 files changed