Added UkmPageLoadMetricsObserver which sends top-level metrics to UKM

components/ukm/ukm_service_unittest.cc

 // Copyright 2017 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/ukm/ukm_service.h"
 
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/metrics/proto/ukm/report.pb.h"
 #include "components/metrics/proto/ukm/source.pb.h"
@@ skipping 89 matching lines @@
 
 TEST_F(UkmServiceTest, SourceSerialization) {
   UkmService service(&prefs_, &client_);
   EXPECT_EQ(GetPersistedLogCount(), 0);
   service.Initialize();
   task_runner_->RunUntilIdle();
   service.EnableReporting();
 
   std::unique_ptr<UkmSource> source = base::WrapUnique(new UkmSource());
   source->set_committed_url(GURL("https://google.com"));
-  base::Time test_time;
-  source->set_navigation_start(test_time);
   source->set_first_contentful_paint(base::TimeDelta::FromMilliseconds(300));
 
   service.RecordSource(std::move(source));
 
   service.Flush();
   EXPECT_EQ(GetPersistedLogCount(), 1);
 
   Report proto_report = GetPersistedReport();
   EXPECT_EQ(1, proto_report.sources_size());
   const Source& proto_source = proto_report.sources(0);
 
   EXPECT_EQ(GURL("https://google.com").spec(), proto_source.url());
-  base::Time navigation_time =
-      base::Time::UnixEpoch() +
-      base::TimeDelta::FromMilliseconds(proto_source.navigation_time_msec());
-  EXPECT_EQ(test_time, navigation_time);
   EXPECT_EQ(300, proto_source.first_contentful_paint_msec());
 }
 
 }  // namespace ukm