web_dev_style: Only run HTMLChecker on .html files

chrome/browser/web_dev_style/html_checker.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 for Chromium HTML resources. See chrome/browser/PRESUBMIT.py.
 """
 
 import regex_check
 
@@ skipping 73 matching lines @@
   def RunChecks(self):
     """Check for violations of the Chromium web development style guide. See
        http://chromium.org/developers/web-development-style-guide
     """
     results = []
 
     affected_files = self.input_api.change.AffectedFiles(
         file_filter=self.file_filter, include_deletes=False)
 
     for f in affected_files:
+      if not f.LocalPath().endswith('.html'):
+        continue
+
       errors = []
 
       for line_number, line in f.ChangedContents():
         errors.extend(filter(None, [
             self.ClassesUseDashFormCheck(line_number, line),
             self.DoNotCloseSingleTagsCheck(line_number, line),
             self.DoNotUseBrElementCheck(line_number, line),
             self.DoNotUseInputTypeButtonCheck(line_number, line),
             self.I18nContentJavaScriptCaseCheck(line_number, line),
             self.LabelCheck(line_number, line),
             self.QuotePolymerBindings(line_number, line),
         ]))
 
       if errors:
         abs_local_path = f.AbsoluteLocalPath()
         file_indicator = 'Found HTML style issues in %s' % abs_local_path
         prompt_msg = file_indicator + '\n\n' + '\n'.join(errors) + '\n'
         results.append(self.output_api.PresubmitPromptWarning(prompt_msg))
 
     return results