Adding previews information to PLM UKM

chrome/browser/page_load_metrics/metrics_web_contents_observer.h

Index: chrome/browser/page_load_metrics/metrics_web_contents_observer.h
diff --git a/chrome/browser/page_load_metrics/metrics_web_contents_observer.h b/chrome/browser/page_load_metrics/metrics_web_contents_observer.h
index a57a65e5963f410332c9f94f0528175069734f9d..7265774332da19cd0cb43b9e1931ce0fa7188e78 100644
--- a/chrome/browser/page_load_metrics/metrics_web_contents_observer.h
+++ b/chrome/browser/page_load_metrics/metrics_web_contents_observer.h
@@ -11,11 +11,13 @@
 
 #include "base/macros.h"
 #include "base/observer_list.h"
+#include "base/optional.h"
 #include "base/time/time.h"
 #include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
 #include "chrome/common/page_load_metrics/page_load_metrics.mojom.h"
 #include "chrome/common/page_load_metrics/page_load_timing.h"
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_data.h"
+#include "components/ukm/ukm_source.h"
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_binding_set.h"
@@ -145,6 +147,15 @@ class MetricsWebContentsObserver
                        const mojom::PageLoadTiming& timing,
                        const mojom::PageLoadMetadata& metadata);
 
+  // Gets the Source ID for the load related to |navigation_handle| if it is
+  // pending, can be empty if the load is not pending.
+  base::Optional<ukm::SourceId> GetUKMSourceIdForNavigationHandle(
+      content::NavigationHandle* navigation_handle);
+
+  // Gets the Source ID for the currently committed load if there is a committed
+  // load.
+  base::Optional<ukm::SourceId> GetUKMSourceForCommittedLoad();
+
  private:
   friend class content::WebContentsUserData<MetricsWebContentsObserver>;