GitLab

Drop references to reference frames before requesting new surfaces to
ensure we don't hold onto them while the Accelerator is changing resolution,
risking reusing a stale buffer.

BUG=chrome-os-partner:35539
TEST=Hangouts, vdatest

Review URL: https://codereview.chromium.org/880773009

Cr-Commit-Position: refs/heads/master@{#313679}