Add GN build for some chrome common, chrome net, and resources targets.

chrome/chrome_common.gypi

 # Copyright (c) 2013 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.
 
 {
   'targets': [
     {
       'target_name': 'common',
       'type': 'static_library',
       'variables': {
@@ skipping 564 matching lines @@
                 '<(template_input_path)',
                 '<@(_outputs)',
               ],
               'message': 'Generating version information',
             },
           ],
         }],
       ],
     },
     {
+      # GN version: //chrome/commoon/net:net
       'target_name': 'common_net',
       'type': 'static_library',
       'sources': [
         'common/net/net_error_info.cc',
         'common/net/net_error_info.h',
         'common/net/net_resource_provider.cc',
         'common/net/net_resource_provider.h',
         'common/net/predictor_common.h',
         'common/net/url_util.cc',
         'common/net/url_util.h',
@@ skipping 62 matching lines @@
             # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
             'msvs_disabled_warnings': [4267, ],
           },
         ],
       ],
     },
     {
       # Protobuf compiler / generator for the safebrowsing client
       # model proto and the client-side detection (csd) request
       # protocol buffer.
+
+      # GN version: //chrome/common/safe_browsing:proto
       'target_name': 'safe_browsing_proto',
       'type': 'static_library',
       'sources': [
         'common/safe_browsing/client_model.proto',
         'common/safe_browsing/crx_info.proto',
         'common/safe_browsing/csd.proto'
       ],
       'variables': {
         'proto_in_dir': 'common/safe_browsing',
         'proto_out_dir': 'chrome/common/safe_browsing',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
     {
       # Protobuf compiler / generator for UMA (User Metrics Analysis).
+
+      # GN version: //chrome/common/metrics/proto:proto
       'target_name': 'metrics_proto',
       'type': 'static_library',
       'sources': [
         'common/metrics/proto/chrome_experiments.proto',
       ],
       'variables': {
         'proto_in_dir': 'common/metrics/proto',
         'proto_out_dir': 'chrome/common/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }