GitLab

Instead of posting input and compositor tasks directly to the
main thread message loop, forward them to the Blink scheduler
so they can be prioritized over other tasks.

BUG=391005

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=290845

Review URL: https://codereview.chromium.org/363383002

Cr-Commit-Position: refs/heads/master@{#293513}