Cherry-pick: aw: Track UI request GL separately from other threads

Clean cherry-pick of chromium

BUG: 16550863, 16708848

Original description:

Track UI and other threads differently in requesting DrawGL. The request
itself is posted through UI thread, so not tracking them separately can
lead to deadlocks. See bug for more detail.

Change-Id: Ic3cd8c30db9f12caaf9a692425447482ea6106fb
3 files changed