Add support for Chrome policy type that references external data

grit/format/policy_templates/writers/adm_writer.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 
 from grit.format.policy_templates.writers import template_writer
 
 
 NEWLINE = '\r\n'
@@ skipping 112 matching lines @@
           value_text = 'NUMERIC ' + str(item['value'])
         else:
           value_text = '"' + item['value'] + '"'
         builder.AddLine('NAME !!%s_DropDown VALUE %s' %
             (item['name'], value_text))
         self._AddGuiString(item['name'] + '_DropDown', item['caption'])
       builder.AddLine('END ITEMLIST', -1)
     builder.AddLine('END PART', -1)
 
   def _WritePolicy(self, policy, key_name, builder):
+    if policy['type'] == 'external':
+      # This type can only be set through cloud policy.
+      return
+
     self._AddGuiString(policy['name'] + '_Policy', policy['caption'])
     builder.AddLine('POLICY !!%s_Policy' % policy['name'], 1)
     self._WriteSupported(builder)
     policy_explain_name = policy['name'] + '_Explain'
     self._AddGuiString(policy_explain_name, policy['desc'])
     builder.AddLine('EXPLAIN !!' + policy_explain_name)
 
     if policy['type'] == 'main':
       builder.AddLine('VALUENAME "%s"' % policy['name'])
       builder.AddLine('VALUEON NUMERIC 1')
@@ skipping 100 matching lines @@
     self.strings = IndentedStringBuilder()
     # Map of strings seen, to avoid duplicates.
     self.strings_seen = {}
     # String buffer for building the policies of the ADM file.
     self.policies = IndentedStringBuilder()
     # String buffer for building the recommended policies of the ADM file.
     self.recommended_policies = IndentedStringBuilder()
 
   def GetTemplateText(self):
     return self.lines.ToString()