Factor management of metrics updates into its own class.

chrome/browser/page_load_metrics/metrics_web_contents_observer.cc

Index: chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
diff --git a/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc b/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
index 29ce7bc4b0fcdad737f236eba370a5b5a615014b..b1875492bf751488a15cb85768142bc895efeada 100644
--- a/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
+++ b/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
@@ -609,13 +609,9 @@ void MetricsWebContentsObserver::OnTimingUpdated(
   if (error)
     return;
 
-  const bool is_main_frame = (render_frame_host->GetParent() == nullptr);
-  if (is_main_frame) {
-    committed_load_->UpdateTiming(timing, metadata);
-  } else {
-    committed_load_->UpdateSubFrameTiming(render_frame_host, timing, metadata);
-  }
+  committed_load_->UpdateTiming(render_frame_host, timing, metadata);
 
+  const bool is_main_frame = (render_frame_host->GetParent() == nullptr);
   for (auto& observer : testing_observers_)
     observer.OnTimingUpdated(is_main_frame, timing, metadata);
 }