GitLab

It has only one client.  Inline the implementation (and simplify, as the
optional src_rect param is always present).

BUG=675977
R=reed@google.com,robertphillips@chromium.org
TBR=danakj@chromium.org

Review-Url: https://codereview.chromium.org/2610323004
Cr-Commit-Position: refs/heads/master@{#442030}