Set some build properties required by goma buildbots
Set some build properties required by goma buildbots

goma buildbot uses
- event.patchSet.ref for ref (e.g. ref/changes/NN/MMMMM/O) of
 patchset-created change (i.e. a patch is uploaded to gerrit for review)
- event.refUpdate.newRev for commit of submitted change.

R=szager
BUG=324161

Review URL: https://codereview.chromium.org/93673003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@237856 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build