Decouple Metrics Initialization from IO Thread Initialization

components/metrics/data_use_tracker_unittest.cc

 // Copyright 2016 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.
 
 #include "components/metrics/data_use_tracker.h"
 
 #include "base/strings/stringprintf.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
@@ skipping 91 matching lines @@
 }  // namespace
 
 TEST(DataUseTrackerTest, CheckUpdateUsagePref) {
   TestDataUsePrefService local_state;
   FakeDataUseTracker data_use_tracker(&local_state);
   local_state.ClearDataUsePrefs();
 
   int user_pref_value = 0;
   int uma_pref_value = 0;
 
-  data_use_tracker.UpdateMetricsUsagePrefsOnUIThread("", 2 * 100, true);
+  data_use_tracker.UpdateMetricsUsagePrefs("", 2 * 100, true);
   local_state.GetDictionary(prefs::kUserCellDataUse)
       ->GetInteger(kTodayStr, &user_pref_value);
   EXPECT_EQ(2 * 100, user_pref_value);
   local_state.GetDictionary(prefs::kUmaCellDataUse)
       ->GetInteger(kTodayStr, &uma_pref_value);
   EXPECT_EQ(0, uma_pref_value);
 
-  data_use_tracker.UpdateMetricsUsagePrefsOnUIThread("UMA", 100, true);
+  data_use_tracker.UpdateMetricsUsagePrefs("UMA", 100, true);
   local_state.GetDictionary(prefs::kUserCellDataUse)
       ->GetInteger(kTodayStr, &user_pref_value);
   EXPECT_EQ(3 * 100, user_pref_value);
   local_state.GetDictionary(prefs::kUmaCellDataUse)
       ->GetInteger(kTodayStr, &uma_pref_value);
   EXPECT_EQ(100, uma_pref_value);
 }
 
 TEST(DataUseTrackerTest, CheckRemoveExpiredEntries) {
   TestDataUsePrefService local_state;
@@ skipping 66 matching lines @@
   can_upload = data_use_tracker.ShouldUploadLogOnCellular(100);
   EXPECT_TRUE(can_upload);
   // this is about 0.49%
   can_upload = data_use_tracker.ShouldUploadLogOnCellular(200);
   EXPECT_TRUE(can_upload);
   can_upload = data_use_tracker.ShouldUploadLogOnCellular(300);
   EXPECT_FALSE(can_upload);
 }
 
 }  // namespace metrics