Add UMA Histogram Manager to Cronet.

components/components_tests.gyp

 # 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.
 
 {
   'variables': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
@@ skipping 141 matching lines @@
             'json_schema/json_schema_validator_unittest.cc',
             'json_schema/json_schema_validator_unittest_base.cc',
             'json_schema/json_schema_validator_unittest_base.h',
             'keyed_service/content/browser_context_dependency_manager_unittest.cc',
             'keyed_service/core/dependency_graph_unittest.cc',
             'language_usage_metrics/language_usage_metrics_unittest.cc',
             'leveldb_proto/proto_database_impl_unittest.cc',
             'login/screens/screen_context_unittest.cc',
             'metrics/compression_utils_unittest.cc',
             'metrics/daily_event_unittest.cc',
+            'metrics/histogram_encoder_unittest.cc',
+            'metrics/histogram_manager_unittest.cc',
             'metrics/machine_id_provider_win_unittest.cc',
             'metrics/metrics_hashes_unittest.cc',
             'metrics/metrics_log_manager_unittest.cc',
             'metrics/metrics_log_unittest.cc',
             'metrics/metrics_reporting_scheduler_unittest.cc',
             'metrics/metrics_service_unittest.cc',
             'metrics/metrics_state_manager_unittest.cc',
             'metrics/persisted_logs_unittest.cc',
             'metrics/profiler/profiler_metrics_provider_unittest.cc',
             'navigation_interception/intercept_navigation_resource_throttle_unittest.cc',
@@ skipping 905 matching lines @@
               'dependencies': [
                 '../base/allocator/allocator.gyp:allocator',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }