Revert "Mac h264: Do not retain CVPixelBufferRefs"

This reverts commit 074273d8b3ebf34c38df90970bdc9174658b3ff0.

BUG=631485

Review URL: https://codereview.chromium.org/2201673002 .

Cr-Commit-Position: refs/branch-heads/2743@{#715}
Cr-Branched-From: 2b3ae3b8090361f8af5a611712fc1a5ab2de53cb-refs/heads/master@{#394939}
1 file changed