The previous script only looked up the LKGR and generated a
commit message. This CL renames the script and makes it update
the DEPS file, commit locally, upload CL and send tryjobs.
BUG=4688
R=phoglund@webrtc.org
Review URL: https://webrtc-codereview.appspot.com/50079004
Cr-Commit-Position: refs/heads/master@{#9284}
