Add support for tracking loading behavior of child frames.

chrome/browser/page_load_metrics/page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_observer.h b/chrome/browser/page_load_metrics/page_load_metrics_observer.h
index 370d95c2dff214c69c641a9dc73ab3eb713ca155..5a667f162bbeaac740263361b05ed398dd42ed5c 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_observer.h
+++ b/chrome/browser/page_load_metrics/page_load_metrics_observer.h
@@ -118,7 +118,8 @@ struct PageLoadExtraInfo {
       PageEndReason page_end_reason,
       UserInitiatedInfo page_end_user_initiated_info,
       const base::Optional<base::TimeDelta>& page_end_time,
-      const PageLoadMetadata& metadata);
+      const PageLoadMetadata& metadata,
+      const PageLoadMetadata& child_frame_metadata);
 
   // Simplified version of the constructor, intended for use in tests.
   static PageLoadExtraInfo CreateForTesting(const GURL& url,
@@ -188,6 +189,9 @@ struct PageLoadExtraInfo {
   // Extra information supplied to the page load metrics system from the
   // renderer.
   const PageLoadMetadata metadata;

[RyanSturm, 2017/03/08 23:54:41]

Can you change this to main_frame_metadata and update the comment?

[Bryan McQuade, 2017/03/09 03:06:12]

good idea, done, thanks!

+
+  // PageLoadMetadata for child frames of the current page load.
+  const PageLoadMetadata child_frame_metadata;
 };
 
 // Container for various information about a request within a page load.
@@ -314,7 +318,8 @@ class PageLoadMetricsObserver {
   virtual void OnParseStop(const PageLoadTiming& timing,
                            const PageLoadExtraInfo& extra_info) {}
 
-  // Invoked when there is a change in PageLoadMetadata's behavior_flags.
+  // Invoked when there is a change in either PageLoadMetadata's behavior_flags,
+  // or the child_frame_metadata's loading_behavior_flags.
   virtual void OnLoadingBehaviorObserved(
       const page_load_metrics::PageLoadExtraInfo& extra_info) {}