Add closure_compilation to `git cl try` for CLs that touch resources

chrome/browser/resources/PRESUBMIT.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Presubmit script for files in chrome/browser/resources.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 102 matching lines @@
     new_description = re.sub(tag_reg, new_tag, description, flags=re.M | re.I)
   else:
     new_description = description + '\n' + new_tag
 
   if new_description == description:
     return []
 
   rietveld_obj.update_description(cl.issue, new_description)
   return [output_api.PresubmitNotifyResult(
       'Automatically added optional Closure bots to run on CQ.')]
+
+
+def GetPreferredTryMasters(project, change):
+  return {
+    'tryserver.chromium.linux': {
+      'closure_compilation': set(['defaulttests']),
+    },
+  }