Add support for tracking loading behavior of child frames.

chrome/browser/page_load_metrics/page_load_tracker.cc

Index: chrome/browser/page_load_metrics/page_load_tracker.cc
diff --git a/chrome/browser/page_load_metrics/page_load_tracker.cc b/chrome/browser/page_load_metrics/page_load_tracker.cc
index f6d8e104267d9e300da4da1dadab01eac9151889..bdd1dab2910077179b18f3b61e052e64a13388e1 100644
--- a/chrome/browser/page_load_metrics/page_load_tracker.cc
+++ b/chrome/browser/page_load_metrics/page_load_tracker.cc
@@ -303,6 +303,7 @@ PageLoadTracker::PageLoadTracker(
       started_in_foreground_(in_foreground),
       page_transition_(navigation_handle->GetPageTransition()),
       user_initiated_info_(user_initiated_info),
+      child_loading_behavior_flags_(0),
       aborted_chain_size_(aborted_chain_size),
       aborted_chain_size_same_url_(aborted_chain_size_same_url),
       embedder_interface_(embedder_interface) {
@@ -506,6 +507,21 @@ void PageLoadTracker::NotifyClientRedirectTo(
   }
 }
 
+void PageLoadTracker::UpdateChildMetadata(
+    const PageLoadMetadata& child_metadata) {
+  // Merge the child loading behavior flags with any we've already observed,
+  // possibly from other child frames.
+  const int last_child_loading_behavior_flags = child_loading_behavior_flags_;
+  child_loading_behavior_flags_ |= child_metadata.behavior_flags;
+  if (last_child_loading_behavior_flags == child_loading_behavior_flags_)
+    return;
+
+  PageLoadExtraInfo extra_info(ComputePageLoadExtraInfo());
+  for (const auto& observer : observers_) {
+    observer->OnLoadingBehaviorObserved(extra_info);
+  }
+}
+
 bool PageLoadTracker::UpdateTiming(const PageLoadTiming& new_timing,
                                    const PageLoadMetadata& new_metadata) {
   // Throw away IPCs that are not relevant to the current navigation.
@@ -615,11 +631,11 @@ PageLoadExtraInfo PageLoadTracker::ComputePageLoadExtraInfo() {
          (!page_end_user_initiated_info_.browser_initiated &&
           !page_end_user_initiated_info_.user_gesture &&
           !page_end_user_initiated_info_.user_input_event));
-  return PageLoadExtraInfo(navigation_start_, first_background_time,
-                           first_foreground_time, started_in_foreground_,
-                           user_initiated_info_, url(), start_url_, did_commit_,
-                           page_end_reason_, page_end_user_initiated_info_,
-                           page_end_time, metadata_);
+  return PageLoadExtraInfo(
+      navigation_start_, first_background_time, first_foreground_time,
+      started_in_foreground_, user_initiated_info_, url(), start_url_,
+      did_commit_, page_end_reason_, page_end_user_initiated_info_,
+      page_end_time, metadata_, child_loading_behavior_flags_);
 }
 
 bool PageLoadTracker::HasMatchingNavigationRequestID(