Add presubmit scripts to check histograms.xml if bad_message.h changes.

content/browser/PRESUBMIT.py

+# Copyright 2017 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.
+"""Chromium presubmit script to check that BadMessage enums in histograms.xml
+match the corresponding bad_message.h file.
+"""
+
+def _RunHistogramChecks(input_api, output_api, histogram_name):
+  try:
+    # Setup sys.path so that we can call histrogram code
+    import sys
+    original_sys_path = sys.path
+    sys.path = sys.path + [input_api.os_path.join(
+      input_api.change.RepositoryRoot(),
+      'tools', 'metrics', 'histograms')]
+
+    import presubmit_bad_message_reasons
+    return presubmit_bad_message_reasons.PrecheckBadMessage(input_api,
+      output_api, histogram_name)
+  except Exception as e:
+    return [output_api.PresubmitError("Error verifying histogram (%s)."
+      % str(e))]
+  finally:
+    sys.path = original_sys_path
+
+def CheckChangeOnUpload(input_api, output_api):
+  return _RunHistogramChecks(input_api, output_api, "BadMessageReasonContent")