Add support for tracking loading behavior of child frames.

chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc

Index: chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
diff --git a/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc b/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
index 006eda7b705f3eafe5aa4a37ca654a8c37077421..991a41c98c990eec80bcd804c408bf939e359a45 100644
--- a/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
+++ b/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
@@ -38,7 +38,9 @@ MetricsRenderFrameObserver::MetricsRenderFrameObserver(
 MetricsRenderFrameObserver::~MetricsRenderFrameObserver() {}
 
 void MetricsRenderFrameObserver::DidChangePerformanceTiming() {
-  SendMetrics();
+  // Only track timing metrics for main frames.
+  if (IsMainFrame())
+    SendMetrics();
 }
 
 void MetricsRenderFrameObserver::DidObserveLoadingBehavior(
@@ -66,8 +68,12 @@ void MetricsRenderFrameObserver::DidCommitProvisionalLoad(
   // non-null, we will send metrics for the current page at some later time, as
   // those metrics become available.
   if (ShouldSendMetrics()) {
-    PageLoadTiming timing(GetTiming());
-    DCHECK(!timing.navigation_start.is_null());
+    PageLoadTiming timing;
+    if (IsMainFrame()) {
+      // Only populate PageLoadTiming for the main frame.
+      timing = GetTiming();
+      DCHECK(!timing.navigation_start.is_null());
+    }
     page_timing_metrics_sender_.reset(
         new PageTimingMetricsSender(this, routing_id(), CreateTimer(), timing));
   }
@@ -86,10 +92,6 @@ bool MetricsRenderFrameObserver::ShouldSendMetrics() const {
   if (HasNoRenderFrame())
     return false;
   const blink::WebLocalFrame* frame = render_frame()->GetWebFrame();
-  // We only track metrics for main frames.
-  if (frame->parent())
-    return false;
-
   const blink::WebDocument& document = frame->document();
   return RendererPageTrackDecider(&document, frame->dataSource()).ShouldTrack();
 }
@@ -171,4 +173,8 @@ void MetricsRenderFrameObserver::OnDestruct() {
   delete this;
 }
 
+bool MetricsRenderFrameObserver::IsMainFrame() const {

[Charlie Harrison, 2017/03/08 21:47:17]

RenderFrame has an IsMainFrame method already. I'm not sure if what you have
works with OOPIF.

[Bryan McQuade, 2017/03/09 03:06:11]

excellent, thanks! i kept this virtual method for overriding in tests, but have
it call render_frame()->IsMainFrame() directly.

+  return render_frame()->GetWebFrame()->parent() == nullptr;
+}
+
 }  // namespace page_load_metrics