Rework UMAHistogramHelper and StatisticsDeltaReader into [Chrome]HistogramTester.

base/BUILD.gn

 # 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.
 
 import("//build/config/ui.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
@@ skipping 1205 matching lines @@
     "synchronization/lock_unittest.cc",
     "synchronization/waitable_event_unittest.cc",
     "synchronization/waitable_event_watcher_unittest.cc",
     "sys_info_unittest.cc",
     "system_monitor/system_monitor_unittest.cc",
     "task/cancelable_task_tracker_unittest.cc",
     "task_runner_util_unittest.cc",
     "template_util_unittest.cc",
     "test/expectations/expectation_unittest.cc",
     "test/expectations/parser_unittest.cc",
-    "test/statistics_delta_reader_unittest.cc",
+    "test/histogram_tester_unittest.cc",
     "test/test_reg_util_win_unittest.cc",
     "test/trace_event_analyzer_unittest.cc",
     "threading/non_thread_safe_unittest.cc",
     "threading/platform_thread_unittest.cc",
     "threading/sequenced_worker_pool_unittest.cc",
     "threading/simple_thread_unittest.cc",
     "threading/thread_checker_unittest.cc",
     "threading/thread_collision_warner_unittest.cc",
     "threading/thread_id_name_manager_unittest.cc",
     "threading/thread_local_storage_unittest.cc",
@@ skipping 217 matching lines @@
 
   unittest_apk("base_unittests_apk") {
     deps = [
       ":base_java",
       ":base_java_unittest_support",
       ":base_unittests",
     ]
     unittests_dep = ":base_unittests"
   }
 }