Include builder_name in full_results in telemetry_unittests.

Turns out we need it to be included in full_results.json as
well as passed as a URL parameter :(.

TBR=ojan@chromium.org, tonyg@chromium.org
BUG=323212

Review URL: https://codereview.chromium.org/474843002

Cr-Commit-Position: refs/heads/master@{#289459}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289459 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/unittest/json_results.py

@@ -80,6 +80,7 @@ def FullResults(args, suite, results):
   full_results['path_delimiter'] = TEST_SEPARATOR
   full_results['version'] = 3
   full_results['seconds_since_epoch'] = time.time()
+  full_results['builder_name'] = args.builder_name or ''
   for md in args.metadata:
     key, val = md.split('=', 1)
     full_results[key] = val