GitLab

OverlayStrategyFullscreen used to promote a quad to an overlay
finding a suitable quad, removing it from the quad_list and
pushing the overlay candidate to the list of overlay candidates.

This behavior was relying on ozone optimization that would
replace the primary plane if there were a fullscreen overlay
on top of it.

This CLs changes OverlayStrategyFullscreen behavior making it more
aggressive.
Once a quad that can be promoted is found, quad_list is erased since
all the quads are either not visible, or covered by the fullscreen
overlay, or the fullscreen overlay itself.

It also clear the overlay_list, that contains the primary buffer,
since the promoted overlay will be replacing it, in this way
we stop relying on the ozone optimization.

BUG=b/29430506
TEST=cc_unittests --gtest_filter="*FullscreenOverlayTest*", also tried it on minnie.
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel

Review-Url: https://codereview.chromium.org/2281033003
Cr-Commit-Position: refs/heads/master@{#414830}