Enable the browser side thumbnailing on Chrome OS.
Enable the browser side thumbnailing on Chrome OS.

BUG=chromium:96351
TEST=Manually checked that jerks did not happen on http://persistent.info/webkit/puzzlers/jerky-animation.html

Change-Id: I381847283ab3b99d0edf649c7ec65bae825046bc
Reviewed-on: https://gerrit.chromium.org/gerrit/18355
Commit-Ready: Yasuhiro Matsuda <9ec2621bb952ab212238ced42dcfb982244bde16@chromium.org>
Reviewed-by: Yasuhiro Matsuda <9ec2621bb952ab212238ced42dcfb982244bde16@chromium.org>
Tested-by: Yasuhiro Matsuda <9ec2621bb952ab212238ced42dcfb982244bde16@chromium.org>

chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager