Move UKM PageLoad SourceId generation to PageLoadTracker.

chrome/browser/page_load_metrics/page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
index e4cf29d718de9b14c3bf632423da5fc3d176dc63..e41ef15448c77ac0523871789c7c791941273e39 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
@@ -21,7 +21,8 @@ PageLoadExtraInfo::PageLoadExtraInfo(
     UserInitiatedInfo page_end_user_initiated_info,
     const base::Optional<base::TimeDelta>& page_end_time,
     const mojom::PageLoadMetadata& main_frame_metadata,
-    const mojom::PageLoadMetadata& subframe_metadata)
+    const mojom::PageLoadMetadata& subframe_metadata,
+    ukm::SourceId source_id)
     : navigation_start(navigation_start),
       first_background_time(first_background_time),
       first_foreground_time(first_foreground_time),
@@ -34,7 +35,8 @@ PageLoadExtraInfo::PageLoadExtraInfo(
       page_end_user_initiated_info(page_end_user_initiated_info),
       page_end_time(page_end_time),
       main_frame_metadata(main_frame_metadata),
-      subframe_metadata(subframe_metadata) {}
+      subframe_metadata(subframe_metadata),
+      source_id(source_id) {}
 
 PageLoadExtraInfo::PageLoadExtraInfo(const PageLoadExtraInfo& other) = default;
 
@@ -53,7 +55,7 @@ PageLoadExtraInfo PageLoadExtraInfo::CreateForTesting(
       page_load_metrics::END_NONE,
       page_load_metrics::UserInitiatedInfo::NotUserInitiated(),
       base::TimeDelta(), page_load_metrics::mojom::PageLoadMetadata(),
-      page_load_metrics::mojom::PageLoadMetadata());
+      page_load_metrics::mojom::PageLoadMetadata(), 0 /* source_id */);
 }
 
 ExtraRequestCompleteInfo::ExtraRequestCompleteInfo(
@@ -102,7 +104,8 @@ PageLoadMetricsObserver::ObservePolicy PageLoadMetricsObserver::OnRedirect(
 }
 
 PageLoadMetricsObserver::ObservePolicy PageLoadMetricsObserver::OnCommit(
-    content::NavigationHandle* navigation_handle) {
+    content::NavigationHandle* navigation_handle,
+    ukm::SourceId source_id) {
   return CONTINUE_OBSERVING;
 }
 
@@ -126,9 +129,14 @@ PageLoadMetricsObserver::FlushMetricsOnAppEnterBackground(
 PageLoadMetricsObserver::ObservePolicy
 PageLoadMetricsObserver::ShouldObserveMimeType(
     const std::string& mime_type) const {
-  return mime_type == "text/html" || mime_type == "application/xhtml+xml"
-             ? CONTINUE_OBSERVING
-             : STOP_OBSERVING;
+  return IsStandardWebPageMimeType(mime_type) ? CONTINUE_OBSERVING
+                                              : STOP_OBSERVING;
+}
+
+// static
+bool PageLoadMetricsObserver::IsStandardWebPageMimeType(
+    const std::string& mime_type) {
+  return mime_type == "text/html" || mime_type == "application/xhtml+xml";
 }
 
 }  // namespace page_load_metrics