cc: Use occlusion for deciding raster/eviction priorities in browser
The browser compositor should use occlusion to allow lots of
overlapping windows to take up less memory. This reduces our memory
consumption in ash a bit.
Though, the window UI is not considered opaque currently, so more
memory is still used than could be otherwise.
R=enne, vmpstr
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/
1277053002
Cr-Commit-Position: refs/heads/master@{#342493}