[On-device adaptive brightness] Implement a controller and add to browser.

Bug: 881215
Change-Id: I504764bd39f586d07e67eef1443565d4235a6a2c
Reviewed-on: https://chromium-review.googlesource.com/c/1322256
Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Jia Meng <jiameng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606770}
5 files changed