Add a HistogramRecorder class and use cases.

base/base.gyp

 # Copyright (c) 2012 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,
   },
   'includes': [
     '../build/win_precompile.gypi',
@@ skipping 846 matching lines @@
             'test/test_file_util_linux.cc',
           ],
         }],
       ],
       'sources': [
         'perftimer.cc',
         'test/expectations/expectation.cc',
         'test/expectations/expectation.h',
         'test/expectations/parser.cc',
         'test/expectations/parser.h',
+        'test/histogram_recorder.cc',
+        'test/histogram_recorder.h',
         'test/mock_chrome_application_mac.h',
         'test/mock_chrome_application_mac.mm',
         'test/mock_devices_changed_observer.cc',
         'test/mock_devices_changed_observer.h',
         'test/mock_time_provider.cc',
         'test/mock_time_provider.h',
         'test/multiprocess_test.cc',
         'test/multiprocess_test.h',
         'test/multiprocess_test_android.cc',
         'test/null_task_runner.cc',
@@ skipping 426 matching lines @@
             'base_unittests.isolate',
           ],
           'sources': [
             'base_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }