Turn new video rendering path on by default, invert flag.
CPU, smoothness, and idle wakeup measures are all drastically improved
and there appear to be no regressions thus far... so flip the flag and
watch the channels for results!
Layout test issues have been fixed by a couple of compositor side CLs
prior to this landing:
http://crrev.com/328220
http://crrev.com/328238
BUG=386551, 396803, 438680, 438766, 439548, 460190
TEST=manual, automated, layout, telemetry.
Review URL: https://codereview.chromium.org/
1125673008
Cr-Commit-Position: refs/heads/master@{#328386}