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These tests use ContentLayer, so change them to use PictureLayer
instead and stop explicitly disabling impl-side painting.

R=enne
BUG=401492

Review URL: https://codereview.chromium.org/443353003

Cr-Commit-Position: refs/heads/master@{#288244}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288244 0039d316-1c4b-4281-b951-d872f2087c98