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This improves the execution speed by a factor 3x, and I think they're
just as correct. Essentially we are waiting until we see a good
aspect ratio, rather than the old behavior which was to wait 10x50 ms
and see if we have a good aspect ratio. This wasn't a problem on fast
machines, but it's a big problem on bots with GPU emulation where
canvas operations are expensive.

BUG=417756
R=perkj@chromium.org,mcasas@chromium.org

Review URL: https://codereview.chromium.org/638423002

Cr-Commit-Position: refs/heads/master@{#299073}