Report page load timing information for child frames.

chrome/browser/page_load_metrics/page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_observer.h b/chrome/browser/page_load_metrics/page_load_metrics_observer.h
index c84787a443019d30ad4dcad76c606d1878f092f1..b6b7ee4718cedd2fc3c9ae72cb1315a7e5e13ad9 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_observer.h
+++ b/chrome/browser/page_load_metrics/page_load_metrics_observer.h
@@ -270,6 +270,8 @@ class PageLoadMetricsObserver {
     STOP_OBSERVING,
   };
 
+  using FrameTreeNodeId = int;
+
   virtual ~PageLoadMetricsObserver() {}
 
   // The page load started, with the given navigation handle.
@@ -335,6 +337,21 @@ class PageLoadMetricsObserver {
   // loading-dev@chromium.org if you intend to override this method.
   virtual void OnTimingUpdate(const PageLoadTiming& timing,
                               const PageLoadExtraInfo& extra_info) {}
+
+  // OnSubFrameTimingUpdate is triggered when an updated PageLoadTiming or
+  // PageLoadMetadata is available for a child frame of the current page
+  // load. The FrameTreeNodeId identifies the frame that
+  // |navigation_start_offset|, |child_timing|, and |child_metadata| are
+  // associated with. |extra_info| contains the extra info associated with the
+  // page. |navigation_start_offset| reports the offset of the subframe's
+  // navigation start from the main frame's navigation_start. The timings
+  // reported in |child_timing| are relative to the subframe's navigation start.
+  virtual void OnSubFrameTimingUpdate(FrameTreeNodeId child_frame_id,

[jkarlin, 2017/05/10 16:55:28]

I'd rather we not create this until a client that needs it (other than tests)
comes along.

[Bryan McQuade, 2017/05/10 18:06:15]

sure - i think i can switch over to using the TestingObserver::OnTimingUpdated
callback once we land the other change.

+                                      base::TimeDelta navigation_start_offset,
+                                      const PageLoadTiming& child_timing,
+                                      const PageLoadMetadata& child_metadata,
+                                      const PageLoadExtraInfo& extra_info) {}
+
   // OnUserInput is triggered when a new user input is passed in to
   // web_contents. Contains a TimeDelta from navigation start.
   virtual void OnUserInput(const blink::WebInputEvent& event) {}
@@ -348,21 +365,29 @@ class PageLoadMetricsObserver {
                                 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 OnFirstMeaningfulPaint(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) {}
 
+  // On*PaintInPage(...) are invoked when the first relevant paint in the page,
+  // across all frames, is observed.
+  virtual void OnFirstPaintInPage(const PageLoadTiming& timing,
+                                  const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstTextPaintInPage(const PageLoadTiming& timing,
+                                      const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstImagePaintInPage(const PageLoadTiming& timing,
+                                       const PageLoadExtraInfo& extra_info) {}
+  virtual void OnFirstContentfulPaintInPage(
+      const PageLoadTiming& timing,
+      const PageLoadExtraInfo& extra_info) {}
+
+  // Unlike other paint callbacks, OnFirstMeaningfulPaintInMainFrameDocument is
+  // tracked per document, and is reported for the main frame document only.
+  virtual void OnFirstMeaningfulPaintInMainFrameDocument(
+      const PageLoadTiming& timing,
+      const PageLoadExtraInfo& extra_info) {}
+
   // Invoked when there is a change in either the main_frame_metadata or the
   // child_frame_metadata's loading behavior_flags.
   virtual void OnLoadingBehaviorObserved(