Include only policy definitions that apply to the platfrom in the policy definition list.

chrome/app/policy/cloud_policy_codegen.gyp

 # Copyright (c) 2011 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'policy_out_dir': '<(SHARED_INTERMEDIATE_DIR)/policy',
     'protoc_out_dir': '<(SHARED_INTERMEDIATE_DIR)/protoc_out',
     'generate_policy_source_script_path':
@@ skipping 30 matching lines @@
           'action_name': 'generate_policy_source',
           'action': [
             'python',
             '<@(generate_policy_source_script_path)',
             '--policy-constants-header=<(policy_constant_header_path)',
             '--policy-constants-source=<(policy_constant_source_path)',
             '--policy-type-header=<(configuration_policy_type_header_path)',
             '--policy-protobuf=<(cloud_policy_proto_path)',
             '--protobuf-decoder=<(protobuf_decoder_path)',
             '<(OS)',
+            '<(chromeos)',
             'policy_templates.json',
           ],
           'message': 'Generating policy source',
         },
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           '<(policy_out_dir)',
           '<(protoc_out_dir)',
         ],
@@ skipping 134 matching lines @@
           'configurations': {
             'Common_Base': {
               'msvs_target_platform': 'x64',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }