Populates navigation time into UKM source proto.

Bug: 928299
Change-Id: I28cf9ad47f7ca05fe9132b3bb64ee2a346a8fc8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1555418Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Auto-Submit: Michael Crouse <mcrouse@chromium.org>
Commit-Queue: Michael Crouse <mcrouse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658733}

components/ukm/content/source_url_recorder.cc

@@ -332,6 +332,8 @@ void SourceUrlRecorderWebContentsObserver::MaybeRecordUrl(
   navigation_data.previous_source_id =
       last_committed_full_navigation_source_id_;
 
+  navigation_data.navigation_time = navigation_handle->NavigationStart();
+
   // If the last_committed_full_navigation_or_same_document_source_id_ isn't
   // equal to the last_committed_full_navigation_source_id_, it indicates the
   // previous source was a same document navigation.

components/ukm/content/source_url_recorder_test.cc

@@ -122,6 +122,7 @@ TEST_F(SourceUrlRecorderWebContentsObserverTest, SameDocumentNavigation) {
   EXPECT_FALSE(full_nav_source1.is_same_document_navigation());
   EXPECT_FALSE(full_nav_source1.has_previous_source_id());
   EXPECT_FALSE(full_nav_source1.has_previous_same_document_source_id());
+  EXPECT_TRUE(full_nav_source1.has_navigation_time_msec());
 
   // The second navigation was a same-document navigation to
   // same_document_url1. It should have a previous_source_id that points to
@@ -131,6 +132,7 @@ TEST_F(SourceUrlRecorderWebContentsObserverTest, SameDocumentNavigation) {
   EXPECT_TRUE(same_doc_source1.is_same_document_navigation());
   EXPECT_EQ(full_nav_source1.id(), same_doc_source1.previous_source_id());
   EXPECT_FALSE(same_doc_source1.has_previous_same_document_source_id());
+  EXPECT_TRUE(same_doc_source1.has_navigation_time_msec());
 
   // The third navigation was a non-same-document navigation to url2. It should
   // have a previous_source_id pointing to the source for url1, and a
@@ -142,6 +144,7 @@ TEST_F(SourceUrlRecorderWebContentsObserverTest, SameDocumentNavigation) {
   EXPECT_EQ(full_nav_source1.id(), full_nav_source2.previous_source_id());
   EXPECT_EQ(same_doc_source1.id(),
             full_nav_source2.previous_same_document_source_id());
+  EXPECT_TRUE(full_nav_source2.has_navigation_time_msec());
 
   // The fourth navigation was a same-document navigation to
   // same_document_url2. It should have a previous_source_id pointing to the
@@ -151,8 +154,17 @@ TEST_F(SourceUrlRecorderWebContentsObserverTest, SameDocumentNavigation) {
   EXPECT_TRUE(same_doc_source2.is_same_document_navigation());
   EXPECT_EQ(full_nav_source2.id(), same_doc_source2.previous_source_id());
   EXPECT_FALSE(same_doc_source2.has_previous_same_document_source_id());
+  EXPECT_TRUE(same_doc_source2.has_navigation_time_msec());
 
   EXPECT_EQ(url2, GetAssociatedURLForWebContentsDocument());
+
+  // The recorded time of each navigation should increase monotonically.
+  EXPECT_LE(full_nav_source1.navigation_time_msec(),
+            same_doc_source1.navigation_time_msec());
+  EXPECT_LE(same_doc_source1.navigation_time_msec(),
+            full_nav_source2.navigation_time_msec());
+  EXPECT_LE(full_nav_source2.navigation_time_msec(),
+            same_doc_source2.navigation_time_msec());
 }
 
 TEST_F(SourceUrlRecorderWebContentsObserverTest,

services/metrics/public/cpp/ukm_source.cc

@@ -64,6 +64,7 @@ UkmSource::NavigationData UkmSource::NavigationData::CopyWithSanitizedUrls(
   sanitized_navigation_data.tab_id = tab_id;
   sanitized_navigation_data.is_same_document_navigation =
       is_same_document_navigation;
+  sanitized_navigation_data.navigation_time = navigation_time;
   return sanitized_navigation_data;
 }
 
@@ -129,6 +130,11 @@ void UkmSource::PopulateProto(Source* proto_source) const {
 
   if (navigation_data_.is_same_document_navigation)
     proto_source->set_is_same_document_navigation(true);
+
+  if (navigation_data_.navigation_time) {
+    proto_source->set_navigation_time_msec(
+        navigation_data_.navigation_time->since_origin().InMilliseconds());
+  }
 }
 
 }  // namespace ukm

services/metrics/public/cpp/ukm_source.h

@@ -79,6 +79,10 @@ class METRICS_EXPORT UkmSource {
     // document navigations are fragment navigations, pushState/replaceState,
     // and same page history navigation.
     bool is_same_document_navigation = false;
+
+    // The navigation start time relative to session start. The navigation
+    // time within session should be monotonically increasing.
+    base::Optional<base::TimeTicks> navigation_time;
   };
 
   UkmSource(SourceId id, const GURL& url);

third_party/metrics_proto/ukm/source.proto

@@ -84,8 +84,12 @@ message Source {
   // Flag indicating if the metric was collected while inside a "custom tab".
   optional bool is_custom_tab = 7;
 
-  // Timestamp of navigation to this Source, as seen by the client. Time of
-  // events related to this Source will generally be relative to this timestamp.
+  // Relative time of navigation for this Source, as seen by the client, and is
+  // set for sources of type ukm::SourceIdType::NAVIGATION_ID. Time of events
+  // related to this Source will generally be relative to this timestamp. The
+  // recorded navigation time is in TimeTicks, which is the relative time since
+  // the origin. The origin is platform-specific but is guaranteed to be
+  // monotonically increase within each session.
   optional int64 navigation_time_msec = 3;
 
   // Unique identifier (for a given client_id/session_id) for the tab this