Log an immediate variant of FirstContentfulPaint.

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 abe8fb23a75c63b25fa5ba92c56f576da313bdb0..203b3ea06ee2dc7437301f538fae4b2869e0996f 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
@@ -56,6 +56,8 @@ const char kHistogramFirstImagePaint[] =
     "PageLoad.Timing2.NavigationToFirstImagePaint";
 const char kHistogramFirstContentfulPaint[] =
     "PageLoad.Timing2.NavigationToFirstContentfulPaint";
+const char kHistogramFirstContentfulPaintImmediate[] =
+    "PageLoad.Timing2.NavigationToFirstContentfulPaint.Immediate";
 const char kHistogramDomLoadingToFirstContentfulPaint[] =
     "PageLoad.Timing2.DOMLoadingToFirstContentfulPaint";
 const char kHistogramParseDuration[] = "PageLoad.Timing2.ParseDuration";
@@ -130,6 +132,20 @@ CorePageLoadMetricsObserver::CorePageLoadMetricsObserver() {}
 
 CorePageLoadMetricsObserver::~CorePageLoadMetricsObserver() {}
 
+void CorePageLoadMetricsObserver::OnTimingUpdate(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  if (!logged_first_contentful_paint_from_timing_update_ &&
+      !timing.first_contentful_paint.is_zero()) {
+    if (WasStartedInForegroundEventInForeground(timing.first_contentful_paint,
+                                                info)) {
+      PAGE_LOAD_HISTOGRAM(internal::kHistogramFirstContentfulPaintImmediate,
+                          timing.first_contentful_paint);
+    }
+    logged_first_contentful_paint_from_timing_update_ = true;
+  }
+}
+
 void CorePageLoadMetricsObserver::OnComplete(
     const page_load_metrics::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& info) {