Prototype for improved and generalized immediate event logging.

components/page_load_metrics/browser/page_load_metrics_observer.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_
 #define COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_
 
 #include "base/macros.h"
 #include "components/page_load_metrics/common/page_load_timing.h"
 #include "content/public/browser/navigation_handle.h"
@@ skipping 126 matching lines @@
   // OnComplete is triggered when we are ready to record metrics for this page
   // load. This will happen some time after commit. The PageLoadTiming struct
   // contains timing data and the PageLoadExtraInfo struct contains other useful
   // data collected over the course of the page load. If the load did not
   // receive any timing information, |timing.IsEmpty()| will be true.
   // After this call, the object will be deleted.
   virtual void OnComplete(const PageLoadTiming& timing,
                           const PageLoadExtraInfo& extra_info) {}
 };
 
+class PageLoadMetricsEventObserver {
+ public:
+  void HandleTimingUpdate(const PageLoadTiming& timing,
+                          const PageLoadExtraInfo& extra_info);
+
+ protected:
+  virtual void OnDomContentLoadedEventStart(
+      const PageLoadTiming& timing,
+      const PageLoadExtraInfo& extra_info) {}
+  virtual void OnLoadEventStart(const PageLoadTiming& timing,
+                                const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstLayout(const PageLoadTiming& timing,
+                             const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstPaint(const PageLoadTiming& timing,
+                            const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstTextPaint(const PageLoadTiming& timing,
+                                const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstImagePaint(const PageLoadTiming& timing,
+                                 const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstContentfulPaint(const PageLoadTiming& timing,
+                                      const PageLoadExtraInfo& extra_info) {}
+  virtual void OnParseStart(const PageLoadTiming& timing,
+                            const PageLoadExtraInfo& extra_info) {}
+  virtual void OnParseStop(const PageLoadTiming& timing,
+                           const PageLoadExtraInfo& extra_info) {}
+
+ private:
+  // The last timing provided to OnTimingUpdate.
+  PageLoadTiming last_timing_;
+};
+
 }  // namespace page_load_metrics
 
 #endif  // COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_