Add UMA for shared image read and write access.

Add the GPU.SharedImage.ContentConsumed UMA to trace
how many rastered shared image are never read.

Bug: 985024
Change-Id: I7e8d7af1e322a50176cb4355ed88939166d701a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1720793
Commit-Queue: Peng Huang <penghuang@chromium.org>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686120}
23 files changed