Attempt 2: Update PaintTiming Web Perf APIs for FP & FCP to report swap time

third_party/WebKit/Source/core/paint/PaintTiming.cpp

 // 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.
 
 #include "core/paint/PaintTiming.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/LocalFrameView.h"
@@ skipping 123 matching lines @@
 
 void PaintTiming::NotifyPaintTimingChanged() {
   if (GetSupplementable()->Loader())
     GetSupplementable()->Loader()->DidChangePerformanceTiming();
 }
 
 void PaintTiming::SetFirstPaint(double stamp) {
   if (first_paint_ != 0.0)
     return;
   first_paint_ = stamp;
-  Performance* performance = GetPerformanceInstance(GetFrame());
-  if (performance)
-    performance->AddFirstPaintTiming(first_paint_);
-
   TRACE_EVENT_INSTANT1("loading,rail,devtools.timeline", "firstPaint",
                        TRACE_EVENT_SCOPE_PROCESS, "frame", GetFrame());
   RegisterNotifySwapTime(PaintEvent::kFirstPaint);
 }
 
 void PaintTiming::SetFirstContentfulPaint(double stamp) {
   if (first_contentful_paint_ != 0.0)
     return;
   SetFirstPaint(stamp);
   first_contentful_paint_ = stamp;
-  Performance* performance = GetPerformanceInstance(GetFrame());
-  if (performance)
-    performance->AddFirstContentfulPaintTiming(first_contentful_paint_);
-
   TRACE_EVENT_INSTANT1("loading,rail,devtools.timeline", "firstContentfulPaint",
                        TRACE_EVENT_SCOPE_PROCESS, "frame", GetFrame());
   RegisterNotifySwapTime(PaintEvent::kFirstContentfulPaint);
   GetFrame()->Loader().Progress().DidFirstContentfulPaint();
 }
 
 void PaintTiming::RegisterNotifySwapTime(PaintEvent event) {
   // ReportSwapTime on layerTreeView will queue a swap-promise, the callback is
   // called when the swap for current render frame completes or fails to happen.
   if (!GetFrame() || !GetFrame()->GetPage())
     return;
   if (WebLayerTreeView* layerTreeView =
           GetFrame()->GetPage()->GetChromeClient().GetWebLayerTreeView(
               GetFrame())) {
     layerTreeView->NotifySwapTime(ConvertToBaseCallback(
         WTF::Bind(&PaintTiming::ReportSwapTime,
                   WrapCrossThreadWeakPersistent(this), event)));
   }
 }
 
 void PaintTiming::ReportSwapTime(PaintEvent event,
                                  bool did_swap,
                                  double timestamp) {
   if (!did_swap)
     return;
+  Performance* performance = GetPerformanceInstance(GetFrame());
   switch (event) {
     case PaintEvent::kFirstPaint:
       first_paint_swap_ = timestamp;
+      if (performance)
+        performance->AddFirstPaintTiming(first_paint_);
       return;
     case PaintEvent::kFirstContentfulPaint:
       first_contentful_paint_swap_ = timestamp;
+      if (performance)
+        performance->AddFirstContentfulPaintTiming(first_contentful_paint_);
       return;
     case PaintEvent::kFirstMeaningfulPaint:
       first_meaningful_paint_swap_ = timestamp;
       return;
   }
   NOTREACHED();
 }
 
 }  // namespace blink