This doesn't fix the performance regression mentioned by the bug yet,
but is necessary cleanup to land the fix, and should be separated from
the actual fix.

R=jkummerow@chromium.org
BUG=chromium:534200
LOG=n

Review URL: https://codereview.chromium.org/1345313005

Cr-Commit-Position: refs/heads/master@{#30847}