[scheduler] Experiment with prioritizing compositing based on a budget.

This cl adds an experiment to the CompositorPriorityExperiments class that will
set the compositior to kVeryHighPriority until it exhausts a budget. Once the budget
runs out it will set the compositor back to kNormalPriority until the budget is

Bug: 966177
Change-Id: I62d9b261501c99dbe62efa008cbdbc8acd902f7a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1767956
Commit-Queue: Katie Dillon <kdillon@chromium.org>
Reviewed-by: Scott Haseley <shaseley@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695821}
10 files changed