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The crashes caused by this DCHECK happens when a begin-impl-frame
reports no damage, and then presented without frame end. This CL
fixes it.

Bug: 1043091
Change-Id: Idaef2477f7f2904fec87b202c47a3a9be6b95c42
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2018084Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737461}