Pass MetricsServiceClient into MetricsService, and create a simple stubbed TestMetricsServiceClient…

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 42 matching lines @@
         'metrics/proto/sampled_profile.proto',
         'metrics/proto/system_profile.proto',
         'metrics/proto/user_action_event.proto',
       ],
       'variables': {
         'proto_in_dir': 'metrics/proto',
         'proto_out_dir': 'components/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
+    {
+      # TODO(isherman): Remove all //chrome dependencies on this target, and
+      # merge the files in this target with components_unittests.
+      'target_name': 'metrics_test_support',
+      'type': 'static_library',
+      'include_dirs': [
+        '..',
+      ],
+      'dependencies': [
+        'component_metrics_proto',
+        'metrics',
+      ],
+      'export_dependent_settings': [
+        'component_metrics_proto',
+      ],
+      'sources': [
+        'metrics/test_metrics_service_client.cc',
+        'metrics/test_metrics_service_client.h',
+      ],
+    },
   ],
   'conditions': [
     ['chromeos==1', {
       'targets': [
         {
           'target_name': 'metrics_chromeos',
           'type': 'static_library',
           'sources': [
             'metrics/chromeos/serialization_utils.cc',
             'metrics/chromeos/serialization_utils.h',
             'metrics/chromeos/metric_sample.cc',
             'metrics/chromeos/metric_sample.h',
           ],
           'dependencies': [
             '../base/base.gyp:base',
           ],
         },
       ],
     }],
   ],
 }