git try -t support for Gerrit

If testfilter parameter is passed, put it in to the gerrit tryjob
as a property. Later it will be processed by GerritPoller on Buildbot
master.

R=victorhsieh@chromium.org
BUG=468075

Review URL: https://codereview.chromium.org/1019713002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@294500 0039d316-1c4b-4281-b951-d872f2087c98

trychange.py

@@ -727,6 +727,7 @@ def _SendChangeGerrit(bot_spec, options):
   Gerrit message format: starts with !tryjob, optionally followed by a tryjob
   definition in JSON format:
       buildNames: list of strings specifying build names.
+      build_properties: a dict of build properties.
   """
 
   logging.info('Sending by Gerrit')
@@ -752,9 +753,14 @@ def _SendChangeGerrit(bot_spec, options):
   def FormatMessage():
     # Build job definition.
     job_def = {}
+    build_properties = {}
+    if options.testfilter:
+      build_properties['testfilter'] = options.testfilter
     builderNames = [builder for builder, _ in bot_spec]
     if builderNames:
       job_def['builderNames'] = builderNames
+    if build_properties:
+      job_def['build_properties'] = build_properties
 
     # Format message.
     msg = '!tryjob'