commit 805ae7576195a1d1c93d83751945c39951925776
author Sami Kyostila <skyostil@chromium.org> Wed Jul 18 15:58:20 2018
committer Commit Bot <commit-bot@chromium.org> Wed Jul 18 15:58:20 2018
tree 371634d62363d03ff52bcb1e99d0c4361ab3aeef
parent fa0e1405bc2bbed8ba976749a8369f6c8050b72d

Adjust logic for UI thread priority

This patch adjusts the logic for UI thread priority:

1) The priority is only increased to DISPLAY unless it was lower to
   begin with. Recent versions of Android (O+) automatically set the top
   activity's UI thread's niceness to TOP_APP_PRIORITY_BOOST (-10), so
   by setting the priority to DISPLAY (-4) we were in fact lowering the
   priority.

2) The priority is increased earlier in the start-up flow to minimize
   the chances of descheduling.

We also add a field trial for the first change to evaluate its impact.

BUG=841804
TEST=Manual inspection

Change-Id: I3ec70042be86f2b88bb1ae3a2dd8cba7d87eb807
Reviewed-on: https://chromium-review.googlesource.com/1136648
Commit-Queue: Sami Kyöstilä <skyostil@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576079}