[DO NOT COMMIT] Trace events for layout-based First Meaningful Paint detection

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 805 matching lines @@
 
 static inline void layoutFromRootObject(LayoutObject& root)
 {
     LayoutState layoutState(root);
     root.layout();
 }
 
 void FrameView::prepareLayoutAnalyzer()
 {
     bool isTracing = false;
-    TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("blink.debug.layout"), &isTracing);
+    TRACE_EVENT_CATEGORY_GROUP_ENABLED("blink.user_timing", &isTracing);
     if (!isTracing) {
         m_analyzer.clear();
         return;
     }
     if (!m_analyzer)
         m_analyzer = adoptPtr(new LayoutAnalyzer());
     m_analyzer->reset();
 }
 
 PassOwnPtr<TracedValue> FrameView::analyzerCounters()
 {
     if (!m_analyzer)
         return TracedValue::create();
     OwnPtr<TracedValue> value = m_analyzer->toTracedValue();
     value->setString("host", layoutView()->document().location()->host());
+    value->setInteger("visibleHeight", visibleHeight());
+    value->setInteger("contentsHeightBefore", contentsSize().height());

[paulirish, 2016/04/29 02:41:51]

Are you submitting a CL for these non-font counter values?

[Kunihiko Sakamoto, 2016/05/09 07:33:42]

Sorry for the delay, just sent out https://codereview.chromium.org/1957193002/
for review.

+    value->setInteger("contentsHeightAfter", layoutView()->documentRect().height());
+    value->setBoolean("hasBlankText", FontFaceSet::hasBlankText(*m_frame->document()));
     return value.release();
 }
 
 #define PERFORM_LAYOUT_TRACE_CATEGORIES "blink,benchmark," TRACE_DISABLED_BY_DEFAULT("blink.debug.layout")
 
 void FrameView::performLayout(bool inSubtreeLayout)
 {
     ASSERT(inSubtreeLayout || m_layoutSubtreeRootList.isEmpty());
 
-    TRACE_EVENT_BEGIN0(PERFORM_LAYOUT_TRACE_CATEGORIES, "FrameView::performLayout");
+    TRACE_EVENT_BEGIN0("blink.user_timing", "FrameView::performLayout");
     prepareLayoutAnalyzer();
 
     ScriptForbiddenScope forbidScript;
 
     ASSERT(!isInPerformLayout());
     lifecycle().advanceTo(DocumentLifecycle::InPerformLayout);
 
     // performLayout is the actual guts of layout().
     // FIXME: The 300 other lines in layout() probably belong in other helper functions
     // so that a single human could understand what layout() is actually doing.
@@ skipping 19 matching lines @@
         }
         m_layoutSubtreeRootList.clear();
     } else {
         layoutFromRootObject(*layoutView());
     }
 
     m_frame->document()->fetcher()->updateAllImageResourcePriorities();
 
     lifecycle().advanceTo(DocumentLifecycle::AfterPerformLayout);
 
-    TRACE_EVENT_END1(PERFORM_LAYOUT_TRACE_CATEGORIES, "FrameView::performLayout",
-        "counters", analyzerCounters());
+    TRACE_EVENT_END2("blink.user_timing", "FrameView::performLayout",
+        "counters", analyzerCounters(), "frame", m_frame.get());
 }
 
 void FrameView::scheduleOrPerformPostLayoutTasks()
 {
     if (m_postLayoutTasksTimer.isActive())
         return;
 
     if (!m_inSynchronousPostLayout) {
         m_inSynchronousPostLayout = true;
         // Calls resumeScheduledEvents()
@@ skipping 3163 matching lines @@
     return m_hiddenForThrottling && m_crossOriginForThrottling;
 }
 
 LayoutBox& FrameView::boxForScrollControlPaintInvalidation() const
 {
     ASSERT(layoutView());
     return *layoutView();
 }
 
 } // namespace blink