Collect UMA statistics on which chrome://flags lead to chrome restart on ChromeOS.

chrome/browser/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 Chromium browser code.
 
 This script currently only checks HTML/CSS/JS files in resources/.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl/git cl, and see
 http://www.chromium.org/developers/web-development-style-guide for the rules
 checked for here.
 """
 
 
 def CheckChangeOnUpload(input_api, output_api):
   return _CommonChecks(input_api, output_api)
 
 
 def CheckChangeOnCommit(input_api, output_api):
   return _CommonChecks(input_api, output_api)
 
+# chrome/browser/about_flags_switches_histogram_ids.h
+def _CreateAboutFlagsSwitchesHistogramIdsChecker(input_api, output_api):
+  import sys
+  original_sys_path = sys.path
+
+  try:
+    sys.path.append(input_api.os_path.join(
+        input_api.PresubmitLocalPath(), '..', '..', 'tools',
+        'about_flags_switches_histogram_ids_checker'))
+    from about_flags_switches_histogram_ids_checker \
+        import AboutFlagsSwitchesHistogramIDsChecker
+  finally:
+    sys.path = original_sys_path
+
+  return AboutFlagsSwitchesHistogramIDsChecker(input_api, output_api,
+      path='chrome/browser/about_flags_switches_histogram_ids.h')
 
 def _CommonChecks(input_api, output_api):
   """Checks common to both upload and commit."""
   results = []
 
   path = input_api.os_path
   cwd = input_api.PresubmitLocalPath()
   resources = path.join(cwd, 'resources')
   webui = path.join(cwd, 'ui', 'webui')
 
@@ skipping 26 matching lines @@
       return (maybe_resource.LocalPath() not in BLACKLIST and
           _html_css_js_resource(maybe_resource.AbsoluteLocalPath()))
 
     results.extend(css_checker.CSSChecker(
         input_api, output_api, file_filter=is_resource).RunChecks())
     results.extend(js_checker.JSChecker(
         input_api, output_api, file_filter=is_resource).RunChecks())
   finally:
     sys.path = old_path
 
+  affected_files = (f.AbsoluteLocalPath() for f in input_api.AffectedFiles())
+  if path.join(cwd, 'about_flags_switches_histogram_ids.h') in affected_files :
+    input_api.logging.info("Running AboutFlagsSwitchesHistogramIdsChecker.")
+    results += _CreateAboutFlagsSwitchesHistogramIdsChecker(input_api,
+                                                            output_api).Run()
+
   return results