Fix PRESUBMIT tests for committed files that are not .md or .html

chrome/common/extensions/PRESUBMIT.py

Index: chrome/common/extensions/PRESUBMIT.py
diff --git a/chrome/common/extensions/PRESUBMIT.py b/chrome/common/extensions/PRESUBMIT.py
index 08ff3a5564d1c6e5d10a6626125877c9d10743ff..0f2636b24f55620c215b12abfb63a63d8a4b6039 100644
--- a/chrome/common/extensions/PRESUBMIT.py
+++ b/chrome/common/extensions/PRESUBMIT.py
@@ -25,6 +25,8 @@ LOCAL_PUBLIC_TEMPLATES_PATH = os.path.join('docs',
                                            'templates',
                                            'public')
 
+EXTENSIONS_TO_REMOVE_FOR_CLEAN_URLS = ('.md', '.html')
+
 def _ReadFile(filename):
   with open(filename) as f:
     return f.read()
@@ -48,9 +50,13 @@ def _FindMatchingTemplates(template_name, template_path_list):
   unix_name = _UnixName(template_name)
   for template in template_path_list:
     if unix_name == _UnixName(template.split(os.sep)[-1]):
-      # The docserver expects clean (extensionless) template URLs, so we strip
-      # extensions here when generating the list of matches.
-      matches.append(os.path.splitext(template)[0])
+      basename, ext = os.path.splitext(template)
+      # The docserver expects clean (extensionless) template URLs, so we
+      # strip some extensions here when generating the list of matches.
+      if ext in EXTENSIONS_TO_REMOVE_FOR_CLEAN_URLS:
+        matches.append(basename)
+      else:
+        matches.append(template)
   return matches
 
 def _SanitizeAPIName(name, api_path):