Prototype for improved and generalized immediate event logging.

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 93efe4044dc2d58d40d76605f24d52867893a1ea..f5de2c54aa732dfdb9eef5ada1a08c49c1c037b8 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
@@ -58,6 +58,13 @@ class CorePageLoadMetricsObserver
       content::NavigationHandle* navigation_handle) override;
 
  private:
+  class EventObserver : public page_load_metrics::PageLoadMetricsEventObserver {
+   protected:
+    void OnFirstContentfulPaint(
+        const page_load_metrics::PageLoadTiming& new_timing,
+        const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+  };
+
   // Information related to failed provisional loads.
   // Populated in OnFailedProvisionalLoad and accessed in OnComplete.
   struct FailedProvisionalLoadInfo {
@@ -73,7 +80,7 @@ class CorePageLoadMetricsObserver
                     const page_load_metrics::PageLoadExtraInfo& info);
 
   FailedProvisionalLoadInfo failed_provisional_load_info_;
-  bool logged_first_contentful_paint_from_timing_update_ = false;
+  EventObserver event_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(CorePageLoadMetricsObserver);
 };