Fix generating descriptions of policy template strings

tools/grit/grit/gather/policy_json.py

Index: tools/grit/grit/gather/policy_json.py
diff --git a/tools/grit/grit/gather/policy_json.py b/tools/grit/grit/gather/policy_json.py
index c4545088b6ec06362e9a754289cf719f2d17d717..308fe0d9384501c5ca4934bf03216bb971dc66cc 100644
--- a/tools/grit/grit/gather/policy_json.py
+++ b/tools/grit/grit/gather/policy_json.py
@@ -147,11 +147,13 @@ class PolicyJson(skeleton_gatherer.SkeletonGatherer):
       'caption': 'Caption',
       'label': 'Label',
     }
-    if type == 'policy':
+    if item_type == 'policy':
       return '%s of the policy named %s' % (key_map[key], item['name'])
-    elif type == 'enum_item':
+    elif item_type == 'enum_item':
       return ('%s of the option named %s in policy %s' %
               (key_map[key], item['name'], parent_item['name']))
+    else:
+      raise Exception('Unexpected type %s' % item_type)
 
   def _AddPolicyKey(self, item, item_type, parent_item, key, depth):
     '''Given a policy/enumeration item and a key, adds that key and its value