GitLab

When PictureLayerImpl chooses a scale to raster at, we should accept
tiles at that scale as complete, and not try wait for tiles at some
other scale to be filled in. Such a tiling may not even exist.

R=enne, vmpstr
BUG=406433

Review URL: https://codereview.chromium.org/484363003

Cr-Commit-Position: refs/heads/master@{#291604}