Fix crashes in components/policy/resources/PRESUBMIT.py.

components/policy/resources/PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 # If this presubmit check fails or misbehaves, please complain to
 # mnissler@chromium.org, pastarmovj@chromium.org or joaodasilva@chromium.org.
 
 import itertools
 import sys
 import xml.dom.minidom
@@ skipping 87 matching lines @@
 
 def _CommonChecks(input_api, output_api):
   results = []
   results.extend(_CheckPolicyTemplatesSyntax(input_api, output_api))
 
   os_path = input_api.os_path
   local_path = input_api.PresubmitLocalPath()
   template_path = os_path.join(local_path, 'policy_templates.json')
   affected_files = input_api.AffectedFiles()
   if any(f.AbsoluteLocalPath() == template_path for f in affected_files):
-    policies = _GetPolicyTemplates(template_path)
+    try:
+      policies = _GetPolicyTemplates(template_path)
+    except:
+      results.append(output_api.PresubmitError('Invalid Python/JSON syntax.'))
+      return results
     results.extend(_CheckPolicyTestCases(input_api, output_api, policies))
     results.extend(_CheckPolicyHistograms(input_api, output_api, policies))
 
   return results
 
 
 def CheckChangeOnUpload(input_api, output_api):
   return _CommonChecks(input_api, output_api)
 
 
 def CheckChangeOnCommit(input_api, output_api):
   return _CommonChecks(input_api, output_api)