Send an event to the page load metrics to track resource starting.

chrome/browser/page_load_metrics/page_load_tracker.h

Index: chrome/browser/page_load_metrics/page_load_tracker.h
diff --git a/chrome/browser/page_load_metrics/page_load_tracker.h b/chrome/browser/page_load_metrics/page_load_tracker.h
index 2760b014c2ed1f689010ca5ea55c4c8d576fa37e..9e25c7d38f1c151a519ddba32cb2e6b93c8529c9 100644
--- a/chrome/browser/page_load_metrics/page_load_tracker.h
+++ b/chrome/browser/page_load_metrics/page_load_tracker.h
@@ -225,7 +225,11 @@ class PageLoadTracker {
   // UpdateTiming.
   void UpdateChildFrameMetadata(const PageLoadMetadata& child_metadata);
 
-  void OnLoadedResource(const ExtraRequestInfo& extra_request_info);
+  void OnStartedResource(
+      const ExtraRequestStartInfo& extra_request_started_info);
+
+  void OnLoadedResource(
+      const ExtraRequestCompleteInfo& extra_request_complete_info);
 
   // Signals that we should stop tracking metrics for the associated page load.
   // We may stop tracking a page load if it doesn't meet the criteria for