Add UKM PageEndReason3

This CL slightly updates PageEndReason3 (new version from 2):
* HIDDEN is removed as a page end reason due to the fact that we no
longer flush the metric when the page is hidden.
* APP_ENTER_BACKGROUND is added as a reason as the metric can be
reported when this happens, and it is not a page closure per se.

UKM collection review:
https://docs.google.com/document/d/1nGbQlG5bdrKn_vFzZxIIiIzAGbwooC1n2S4DHYmVivI/

Bug: 1049260
Change-Id: I3ff183d73f36287f3a99590abd552ea15d37e252
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2630746Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844317}

chrome/browser/page_load_metrics/observers/core/ukm_page_load_metrics_observer.cc

@@ -273,7 +273,8 @@ UkmPageLoadMetricsObserver::FlushMetricsOnAppEnterBackground(
   RecordSmoothnessMetrics();
   // Assume that page ends on this method, as the app could be evicted right
   // after.
-  RecordPageEndMetrics(&timing, current_time);
+  RecordPageEndMetrics(&timing, current_time,
+                       /* app_entered_background */ true);
   return STOP_OBSERVING;
 }
 
@@ -312,7 +313,8 @@ void UkmPageLoadMetricsObserver::OnFailedProvisionalLoad(
   if (is_portal_)
     return;
 
-  RecordPageEndMetrics(nullptr, base::TimeTicks());
+  RecordPageEndMetrics(nullptr, base::TimeTicks(),
+                       /* app_entered_background */ false);
   if (was_hidden_)
     return;
 
@@ -350,7 +352,8 @@ void UkmPageLoadMetricsObserver::OnComplete(
   ReportLayoutStability();
   RecordSmoothnessMetrics();
   ReportPerfectHeuristicsMetrics();
-  RecordPageEndMetrics(&timing, current_time);
+  RecordPageEndMetrics(&timing, current_time,
+                       /* app_entered_background */ false);
   RecordMobileFriendlinessMetrics();
 }
 
@@ -1088,7 +1091,8 @@ void UkmPageLoadMetricsObserver::RecordMobileFriendlinessMetrics() {
 
 void UkmPageLoadMetricsObserver::RecordPageEndMetrics(
     const page_load_metrics::mojom::PageLoadTiming* timing,
-    base::TimeTicks page_end_time) {
+    base::TimeTicks page_end_time,
+    bool app_entered_background) {
   ukm::builders::PageLoad builder(GetDelegate().GetPageUkmSourceId());
   // page_transition_ fits in a uint32_t, so we can safely cast to int64_t.
   builder.SetNavigation_PageTransition(static_cast<int64_t>(page_transition_));
@@ -1097,10 +1101,11 @@ void UkmPageLoadMetricsObserver::RecordPageEndMetrics(
   // to int64_t.
   int64_t page_end_reason = GetDelegate().GetPageEndReason();
   if (page_end_reason == page_load_metrics::PageEndReason::END_NONE &&
-      was_hidden_) {
-    page_end_reason = page_load_metrics::PageEndReason::END_HIDDEN;
+      app_entered_background) {
+    page_end_reason =
+        page_load_metrics::PageEndReason::END_APP_ENTER_BACKGROUND;
   }
-  builder.SetNavigation_PageEndReason2(page_end_reason);
+  builder.SetNavigation_PageEndReason3(page_end_reason);
   bool is_user_initiated_navigation =
       // All browser initiated page loads are user-initiated.
       GetDelegate().GetUserInitiatedInfo().browser_initiated ||

chrome/browser/page_load_metrics/observers/core/ukm_page_load_metrics_observer.h

@@ -181,7 +181,8 @@ class UkmPageLoadMetricsObserver
   // loads.
   void RecordPageEndMetrics(
       const page_load_metrics::mojom::PageLoadTiming* timing,
-      base::TimeTicks page_end_time);
+      base::TimeTicks page_end_time,
+      bool app_entered_background);
 
   // Records a score from the SiteEngagementService. Called when the page
   // becomes hidden, or at the end of the session if the page is never hidden.

chrome/browser/page_load_metrics/observers/core/ukm_page_load_metrics_observer_unittest.cc

@@ -269,7 +269,7 @@ TEST_F(UkmPageLoadMetricsObserverTest, Basic) {
         kv.second.get(), PageLoad::kNavigation_PageTransitionName,
         ui::PAGE_TRANSITION_LINK);
     tester()->test_ukm_recorder().ExpectEntryMetric(
-        kv.second.get(), PageLoad::kNavigation_PageEndReason2Name,
+        kv.second.get(), PageLoad::kNavigation_PageEndReason3Name,
         page_load_metrics::END_CLOSE);
     tester()->test_ukm_recorder().ExpectEntryMetric(
         kv.second.get(), PageLoad::kParseTiming_NavigationToParseStartName,
@@ -328,7 +328,7 @@ TEST_F(UkmPageLoadMetricsObserverTest, FailedProvisionalLoad) {
         kv.second.get(), PageLoad::kNavigation_PageTransitionName,
         ui::PAGE_TRANSITION_LINK);
     tester()->test_ukm_recorder().ExpectEntryMetric(
-        kv.second.get(), PageLoad::kNavigation_PageEndReason2Name,
+        kv.second.get(), PageLoad::kNavigation_PageEndReason3Name,
         page_load_metrics::END_PROVISIONAL_LOAD_FAILED);
     tester()->test_ukm_recorder().ExpectEntryMetric(
         kv.second.get(),
@@ -477,7 +477,7 @@ TEST_F(UkmPageLoadMetricsObserverTest,
   EXPECT_FALSE(tester()->test_ukm_recorder().EntryHasMetric(
       entry, PageLoad::kPaintTiming_NavigationToLargestContentfulPaint2Name));
   tester()->test_ukm_recorder().ExpectEntryMetric(
-      entry, PageLoad::kNavigation_PageEndReason2Name,
+      entry, PageLoad::kNavigation_PageEndReason3Name,
       page_load_metrics::END_CLOSE);
 
   std::map<ukm::SourceId, ukm::mojom::UkmEntryPtr> internal_merged_entries =
@@ -510,7 +510,7 @@ TEST_F(UkmPageLoadMetricsObserverTest, AbortNeverForegrounded) {
   EXPECT_EQ(1ul, merged_entries.size());
   const ukm::mojom::UkmEntry* entry = merged_entries.begin()->second.get();
   tester()->test_ukm_recorder().ExpectEntryMetric(
-      entry, PageLoad::kNavigation_PageEndReason2Name,
+      entry, PageLoad::kNavigation_PageEndReason3Name,
       page_load_metrics::END_CLOSE);
   tester()->test_ukm_recorder().ExpectEntryMetric(
       entry, PageLoad::kExperimental_PageLoadTypeName,
@@ -552,7 +552,7 @@ TEST_F(UkmPageLoadMetricsObserverTest, FCPPlusPlus_DiscardBackgroundResult) {
   EXPECT_FALSE(tester()->test_ukm_recorder().EntryHasMetric(
       entry, PageLoad::kPaintTiming_NavigationToLargestContentfulPaint2Name));
   tester()->test_ukm_recorder().ExpectEntryMetric(
-      entry, PageLoad::kNavigation_PageEndReason2Name,
+      entry, PageLoad::kNavigation_PageEndReason3Name,
       page_load_metrics::END_CLOSE);
 
   std::map<ukm::SourceId, ukm::mojom::UkmEntryPtr> internal_merged_entries =
@@ -1140,7 +1140,7 @@ TEST_F(UkmPageLoadMetricsObserverTest, MultiplePageLoads) {
   tester()->test_ukm_recorder().ExpectEntrySourceHasUrl(entry1,
                                                         GURL(kTestUrl1));
   tester()->test_ukm_recorder().ExpectEntryMetric(
-      entry1, PageLoad::kNavigation_PageEndReason2Name,
+      entry1, PageLoad::kNavigation_PageEndReason3Name,
       page_load_metrics::END_NEW_NAVIGATION);
   tester()->test_ukm_recorder().ExpectEntryMetric(
       entry1, PageLoad::kPaintTiming_NavigationToFirstContentfulPaintName, 200);
@@ -1154,7 +1154,7 @@ TEST_F(UkmPageLoadMetricsObserverTest, MultiplePageLoads) {
   tester()->test_ukm_recorder().ExpectEntrySourceHasUrl(entry2,
                                                         GURL(kTestUrl2));
   tester()->test_ukm_recorder().ExpectEntryMetric(
-      entry2, PageLoad::kNavigation_PageEndReason2Name,
+      entry2, PageLoad::kNavigation_PageEndReason3Name,
       page_load_metrics::END_CLOSE);
   EXPECT_FALSE(tester()->test_ukm_recorder().EntryHasMetric(
       entry2, PageLoad::kParseTiming_NavigationToParseStartName));
@@ -1484,7 +1484,7 @@ TEST_F(UkmPageLoadMetricsObserverTest, LayoutInstability) {
             kLayoutInstability_CumulativeShiftScore_MainFrame_BeforeInputOrScrollName,
         100);
     ukm_recorder.ExpectEntryMetric(kv.second.get(),
-                                   PageLoad::kNavigation_PageEndReason2Name,
+                                   PageLoad::kNavigation_PageEndReason3Name,
                                    page_load_metrics::END_CLOSE);
   }
 
@@ -1867,6 +1867,23 @@ TEST_F(UkmPageLoadMetricsObserverTest, LCPHiddenWhileFlushing) {
           true /* test_main_frame */);
 }
 
+TEST_F(UkmPageLoadMetricsObserverTest, AppEnterBackground) {
+  NavigateAndCommit(GURL(kTestUrl1));
+  page_load_metrics::mojom::PageLoadTiming timing;
+  page_load_metrics::InitPageLoadTimingForTest(&timing);
+
+  tester()->SimulateAppEnterBackground();
+
+  const auto& ukm_recorder = tester()->test_ukm_recorder();
+  std::map<ukm::SourceId, ukm::mojom::UkmEntryPtr> merged_entries =
+      ukm_recorder.GetMergedEntriesByName(PageLoad::kEntryName);
+  EXPECT_EQ(1ul, merged_entries.size());
+  const ukm::mojom::UkmEntry* entry = merged_entries.begin()->second.get();
+  tester()->test_ukm_recorder().ExpectEntryMetric(
+      entry, PageLoad::kNavigation_PageEndReason3Name,
+      page_load_metrics::END_APP_ENTER_BACKGROUND);
+}
+
 class TestOfflinePreviewsUkmPageLoadMetricsObserver
     : public UkmPageLoadMetricsObserver {
  public:
@@ -1912,7 +1929,7 @@ TEST_F(OfflinePreviewsUKMPageLoadMetricsObserverTest, OfflinePreviewReported) {
     tester()->test_ukm_recorder().ExpectEntrySourceHasUrl(kv.second.get(),
                                                           GURL(kTestUrl1));
     tester()->test_ukm_recorder().ExpectEntryMetric(
-        kv.second.get(), PageLoad::kNavigation_PageEndReason2Name,
+        kv.second.get(), PageLoad::kNavigation_PageEndReason3Name,
         page_load_metrics::END_CLOSE);
   }
 }

components/page_load_metrics/common/page_end_reason.h

@@ -17,7 +17,7 @@ namespace page_load_metrics {
 enum PageEndReason {
   // Page lifetime has not yet ended (page is still active). Pages that
   // become hidden are logged in END_HIDDEN, so we expect low numbers in this
-  // bucket from the end of May 2020, i.e. in Navigation.PageEndReason2.
+  // bucket from the end of May 2020.
   END_NONE = 0,
 
   // The page was reloaded, possibly by the user.
@@ -53,9 +53,14 @@ enum PageEndReason {
   END_OTHER = 9,
 
   // The page became hidden but is still active. Added end of May 2020 for
-  // Navigation.PageEndReason2.
+  // Navigation.PageEndReason2. Deprecated Jan 2021 with
+  // Navigation.PageEndReason3.
   END_HIDDEN = 10,
 
+  // The page load has not yet ended but we need to flush the metrics because
+  // the app has entered the background.
+  END_APP_ENTER_BACKGROUND = 11,
+
   PAGE_END_REASON_COUNT
 };
 

tools/metrics/histograms/enums.xml

@@ -56624,6 +56624,9 @@ Called by update_net_trust_anchors.py.-->
   <int value="10" label="END_HIDDEN">
     Page became hidden, but is still active.
   </int>
+  <int value="11" label="END_APP_BACKGROUND">
+    The metrics were flushed because the app entered the background.
+  </int>
 </enum>
 
 <enum name="PageLifecycleStateTransition">

tools/metrics/ukm/ukm.xml

@@ -10152,6 +10152,9 @@ be describing additional metrics about the same event.
     </summary>
   </metric>
   <metric name="Navigation.PageEndReason2" enum="PageEndReason">
+    <obsolete>
+      Deprecated Jan 2021 in favor of Navigation.PageEndReason3.
+    </obsolete>
     <summary>
       The |page_load_metrics::PageEndReason| for the main frame navigation of
       this page load. Replaced Navigation.PageEndReason at the end of May 2020
@@ -10160,6 +10163,14 @@ be describing additional metrics about the same event.
       metric is recorded after the page became hidden.
     </summary>
   </metric>
+  <metric name="Navigation.PageEndReason3" enum="PageEndReason">
+    <summary>
+      The |page_load_metrics::PageEndReason| for the main frame navigation of
+      this page load. Replaced Navigation.PageEndReason2 on January 2021 to get
+      rid of END_HIDDEN and use END_APP_BACKGROUND on cases where the metrics
+      are flushed and the app enters the background.
+    </summary>
+  </metric>
   <metric name="Navigation.PageTransition">
     <summary>
       The |ui::PageTransition| for the main frame navigation of this page load.