Exempt video MediaStreams from stricter WakeLock requirements.

These are usually associated with an active camera session, are very
small, and don't have audio. We probably should just hold the wake
lock when the camera is on, but that's a bit in tension with privacy
gains by letting screen lock shut it off.

This restores the pre-M113 behavior for video MediaStreams. We should
probably have a fixed minimum size too, but I couldn't find an easy
way to do that.

Bug: 1446737

Change-Id: Iea421375fed34da5dc04b7060784224a6cfda0f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4545813


Commit-Queue: Frank Liberato <liberato@chromium.org>
Reviewed-by: Frank Liberato <liberato@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1149407}