LoadingMetrics: Add UKMs for loading breakdown metrics for navigation

This CL adds UKMs for loading breakdown metrics for navigation. These
are the same as the existing UMAs for loading breakdown metrics. We
record these metrics when the current page navigates away like other
PageLoad metrics.

In page_load_metrics_browsertest.cc, this CL wraps |histogram_tester_|
with std::unique_ptr so that we can swap it with a new instance in the
CachedPage testcase. This makes behavior of the UMA tester aligned with
behavior of the UKM recorder, and code becomes simpler.

UKM Privacy Review (Google-internal):
https://docs.google.com/document/d/1Doc2E2XgCDbC2KI6M71_aA3XH7S61wBYaDSY3vLTOuk/edit?usp=sharing

DesignDoc:
https://docs.google.com/document/d/16oqu9lyPbfgZIjQsRaCfaKE8r1Cdlb3d4GVSdth4AN8/edit?usp=sharing

Change-Id: If58eb2d5626d465d8fa2a06ca0fd9049295408af
Bug: 1068843
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2193194
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782338}

chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc

@@ -219,6 +219,7 @@ UkmPageLoadMetricsObserver::ObservePolicy UkmPageLoadMetricsObserver::OnCommit(
   // The PageTransition for the navigation may be updated on commit.
   page_transition_ = navigation_handle->GetPageTransition();
   was_cached_ = navigation_handle->WasResponseCached();
+  navigation_handle_timing_ = navigation_handle->GetNavigationHandleTiming();
   RecordNoStatePrefetchMetrics(navigation_handle, source_id);
   RecordGeneratedNavigationUKM(source_id, navigation_handle->GetURL());
   navigation_is_cross_process_ = !navigation_handle->IsSameProcess();
@@ -237,6 +238,7 @@ UkmPageLoadMetricsObserver::FlushMetricsOnAppEnterBackground(
     return STOP_OBSERVING;
 
   if (!was_hidden_) {
+    RecordNavigationTimingMetrics();
     RecordPageLoadMetrics(base::TimeTicks::Now(), true /* became_hidden */);
     RecordTimingMetrics(timing);
     RecordInputTimingMetrics();
@@ -251,6 +253,7 @@ UkmPageLoadMetricsObserver::ObservePolicy UkmPageLoadMetricsObserver::OnHidden(
     return CONTINUE_OBSERVING;
 
   if (!was_hidden_) {
+    RecordNavigationTimingMetrics();
     RecordPageLoadMetrics(base::TimeTicks() /* no app_background_time */,
                           true /* became_hidden */);
     RecordTimingMetrics(timing);
@@ -288,6 +291,7 @@ void UkmPageLoadMetricsObserver::OnComplete(
     return;
 
   if (!was_hidden_) {
+    RecordNavigationTimingMetrics();
     RecordPageLoadMetrics(base::TimeTicks() /* no app_background_time */,
                           false /* became_hidden */);
     RecordTimingMetrics(timing);
@@ -344,6 +348,72 @@ void UkmPageLoadMetricsObserver::OnLoadedResource(
   }
 }
 
+void UkmPageLoadMetricsObserver::RecordNavigationTimingMetrics() {
+  const base::TimeTicks navigation_start_time =
+      GetDelegate().GetNavigationStart();
+  const content::NavigationHandleTiming& timing = navigation_handle_timing_;
+
+  // Record metrics for navigation only when all relevant milestones are
+  // recorded and in the expected order. It is allowed that they have the same
+  // value for some cases (e.g., internal redirection for HSTS).
+  if (navigation_start_time.is_null() ||
+      timing.first_request_start_time.is_null() ||
+      timing.first_response_start_time.is_null() ||
+      timing.first_loader_callback_time.is_null() ||
+      timing.final_request_start_time.is_null() ||
+      timing.final_response_start_time.is_null() ||
+      timing.final_loader_callback_time.is_null() ||
+      timing.navigation_commit_sent_time.is_null()) {
+    return;
+  }
+  // TODO(https://crbug.com/1076710): Change these early-returns to DCHECKs
+  // after the issue 1076710 is fixed.
+  if (navigation_start_time > timing.first_request_start_time ||
+      timing.first_request_start_time > timing.first_response_start_time ||
+      timing.first_response_start_time > timing.first_loader_callback_time ||
+      timing.first_loader_callback_time > timing.navigation_commit_sent_time) {
+    return;
+  }
+  if (navigation_start_time > timing.final_request_start_time ||
+      timing.final_request_start_time > timing.final_response_start_time ||
+      timing.final_response_start_time > timing.final_loader_callback_time ||
+      timing.final_loader_callback_time > timing.navigation_commit_sent_time) {
+    return;
+  }
+  DCHECK_LE(timing.first_request_start_time, timing.final_request_start_time);
+  DCHECK_LE(timing.first_response_start_time, timing.final_response_start_time);
+  DCHECK_LE(timing.first_loader_callback_time,
+            timing.final_loader_callback_time);
+
+  ukm::builders::NavigationTiming builder(GetDelegate().GetSourceId());
+
+  // Record the elapsed time from the navigation start milestone.
+  builder
+      .SetFirstRequestStart(
+          (timing.first_request_start_time - navigation_start_time)
+              .InMilliseconds())
+      .SetFirstResponseStart(
+          (timing.first_response_start_time - navigation_start_time)
+              .InMilliseconds())
+      .SetFirstLoaderCallback(
+          (timing.first_loader_callback_time - navigation_start_time)
+              .InMilliseconds())
+      .SetFinalRequestStart(
+          (timing.final_request_start_time - navigation_start_time)
+              .InMilliseconds())
+      .SetFinalResponseStart(
+          (timing.final_response_start_time - navigation_start_time)
+              .InMilliseconds())
+      .SetFinalLoaderCallback(
+          (timing.final_loader_callback_time - navigation_start_time)
+              .InMilliseconds())
+      .SetNavigationCommitSent(
+          (timing.navigation_commit_sent_time - navigation_start_time)
+              .InMilliseconds());
+
+  builder.Record(ukm::UkmRecorder::Get());
+}
+
 void UkmPageLoadMetricsObserver::RecordTimingMetrics(
     const page_load_metrics::mojom::PageLoadTiming& timing) {
   ukm::builders::PageLoad builder(GetDelegate().GetSourceId());

chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.h

@@ -97,6 +97,8 @@ class UkmPageLoadMetricsObserver
   virtual bool IsOfflinePreview(content::WebContents* web_contents) const;
 
  private:
+  void RecordNavigationTimingMetrics();
+
   // Records page load timing related metrics available in PageLoadTiming, such
   // as first contentful paint.
   void RecordTimingMetrics(
@@ -180,6 +182,7 @@ class UkmPageLoadMetricsObserver
   base::TimeDelta total_foreground_cpu_time_;
 
   // Load timing metrics of the main frame resource request.
+  content::NavigationHandleTiming navigation_handle_timing_;
   base::Optional<net::LoadTimingInfo> main_frame_timing_;
 
   // PAGE_TRANSITION_LINK is the default PageTransition value.

chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer_unittest.cc

@@ -1795,3 +1795,36 @@ TEST_F(OfflinePreviewsUKMPageLoadMetricsObserverTest, OfflinePreviewReported) {
         page_load_metrics::END_CLOSE);
   }
 }
+
+TEST_F(UkmPageLoadMetricsObserverTest, NavigationTiming) {
+  GURL url(kTestUrl1);
+  NavigateAndCommit(url);
+
+  // Simulate closing the tab.
+  DeleteContents();
+
+  using ukm::builders::NavigationTiming;
+  std::map<ukm::SourceId, ukm::mojom::UkmEntryPtr> merged_entries =
+      tester()->test_ukm_recorder().GetMergedEntriesByName(
+          NavigationTiming::kEntryName);
+  EXPECT_EQ(1ul, merged_entries.size());
+
+  const std::vector<const char*> metrics = {
+      NavigationTiming::kFirstRequestStartName,
+      NavigationTiming::kFirstResponseStartName,
+      NavigationTiming::kFirstLoaderCallbackName,
+      NavigationTiming::kFinalRequestStartName,
+      NavigationTiming::kFinalResponseStartName,
+      NavigationTiming::kFinalLoaderCallbackName,
+      NavigationTiming::kNavigationCommitSentName};
+
+  for (const auto& kv : merged_entries) {
+    tester()->test_ukm_recorder().ExpectEntrySourceHasUrl(kv.second.get(), url);
+
+    // Verify if the elapsed times from the navigation start are recorded.
+    for (const char* metric : metrics) {
+      EXPECT_TRUE(tester()->test_ukm_recorder().EntryHasMetric(kv.second.get(),
+                                                               metric));
+    }
+  }
+}