Use wtf_size_t for frame index accessing frame buffer cache.

BUG=879657

Change-Id: Ifc3ba15e517c79286158e77a8bb83c3c30ea1a75
Reviewed-on: https://chromium-review.googlesource.com/c/1355881
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612413}
2 files changed