Report page load timing information for child frames.

chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
index 35c6beeda021730506fd99fdc5a69f7f9fbfaad9..2a65a7524251454867214d5d5b2ed731d84f3b45 100644
--- a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
@@ -326,6 +326,9 @@ void CorePageLoadMetricsObserver::OnFirstLayout(
 void CorePageLoadMetricsObserver::OnFirstPaint(
     const page_load_metrics::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& info) {
+  if (!first_paint_.is_null())
+    return;
+
   first_paint_ =
       info.navigation_start + timing.paint_timing.first_paint.value();
   if (WasStartedInForegroundOptionalEventInForeground(
@@ -684,6 +687,29 @@ void CorePageLoadMetricsObserver::OnLoadedResource(
   }
 }
 
+void CorePageLoadMetricsObserver::OnSubFrameTimingUpdate(
+    FrameTreeNodeId child_frame_id,
+    base::TimeDelta child_navigation_start,
+    const page_load_metrics::PageLoadTiming& child_timing,
+    const page_load_metrics::PageLoadMetadata& child_metadata,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  // TODO(bmcquade): factor core FP/FCP logic across all frames into
+  // PageLoadTracker. This is just an initial implementation for demonstration
+  // purposes.
+  if (child_timing.paint_timing.first_paint && first_paint_.is_null()) {
+    base::TimeDelta first_paint_since_main_frame_navigation_start =
+        child_navigation_start + child_timing.paint_timing.first_paint.value();
+    first_paint_ = extra_info.navigation_start +
+                   first_paint_since_main_frame_navigation_start;
+
+    if (WasStartedInForegroundOptionalEventInForeground(
+            first_paint_since_main_frame_navigation_start, extra_info)) {
+      PAGE_LOAD_HISTOGRAM(internal::kHistogramFirstPaint,
+                          first_paint_since_main_frame_navigation_start);
+    }
+  }
+}
+
 void CorePageLoadMetricsObserver::RecordTimingHistograms(
     const page_load_metrics::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& info) {