Make chrome/common compile in GN

components/metrics.gypi

 # Copyright 2014 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': 'metrics',
       'type': 'static_library',
       'include_dirs': [
@@ skipping 61 matching lines @@
         '../net/net.gyp:net',
         'metrics',
       ],
       'sources': [
         'metrics/net/net_metrics_log_uploader.cc',
         'metrics/net/net_metrics_log_uploader.h',
       ],
     },
     {
       # Protobuf compiler / generator for UMA (User Metrics Analysis).
+      #
+      # GN version: //component/metrics/proto:proto
       'target_name': 'component_metrics_proto',
       'type': 'static_library',
       'sources': [
         'metrics/proto/chrome_user_metrics_extension.proto',
         'metrics/proto/histogram_event.proto',
         'metrics/proto/omnibox_event.proto',
         'metrics/proto/omnibox_input_type.proto',
         'metrics/proto/perf_data.proto',
         'metrics/proto/profiler_event.proto',
         'metrics/proto/sampled_profile.proto',
@@ skipping 40 matching lines @@
             'metrics/chromeos/metric_sample.h',
           ],
           'dependencies': [
             '../base/base.gyp:base',
           ],
         },
       ],
     }],
   ],
 }