Add immediate variants of core page load metric histograms.

chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
index a7a029e5835cdd73c2ff1c06cd26ee0970f3660b..67a24ff6c7264080041340c092f2e072e17f97fd 100644
--- a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
+++ b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
@@ -49,9 +49,33 @@ class CorePageLoadMetricsObserver
   ~CorePageLoadMetricsObserver() override;
 
   // page_load_metrics::PageLoadMetricsObserver:
+  void OnDomContentLoadedEventStart(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnLoadEventStart(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnFirstLayout(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnFirstPaint(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnFirstTextPaint(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnFirstImagePaint(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
   void OnFirstContentfulPaint(
       const page_load_metrics::PageLoadTiming& timing,
-      const page_load_metrics::PageLoadExtraInfo& info) override;
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnParseStart(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  void OnParseStop(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
   void OnComplete(const page_load_metrics::PageLoadTiming& timing,
                   const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnFailedProvisionalLoad(