Wake Lock API: Implement Screen WakeLock based on Promises.

This patch implements navigator.getWakeLock(WakeLockType) and other
necessary interfaces such as WakeLock and WakeLockRequest to provide
acesss to Screen wakelock for now. Latest WakeLock API spec can be
seen here, https://www.w3.org/TR/wake-lock.

Intent to Implement,
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/KMNZmMF1_H4

Bug: 257511
Change-Id: I7fa4d0f7f287d7497b48f583e18e0ca5ca39e662
Reviewed-on: https://chromium-review.googlesource.com/918062
Commit-Queue: Mrunal Kapade <mrunal.kapade@intel.com>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584239}
35 files changed