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

third_party/WebKit/Source/core/css/RemoteFontFaceSource.h

 // Copyright 2014 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 RemoteFontFaceSource_h
 #define RemoteFontFaceSource_h
 
 #include "core/css/CSSFontFaceSource.h"
 #include "core/fetch/FontResource.h"
 #include "wtf/Allocator.h"
@@ skipping 29 matching lines @@
 
     void notifyFinished(Resource*) override;
     void fontLoadShortLimitExceeded(FontResource*) override;
     void fontLoadLongLimitExceeded(FontResource*) override;
     String debugName() const override { return "RemoteFontFaceSource"; }
 
     // For UMA reporting
     bool hadBlankText() override { return m_histograms.hadBlankText(); }
     void paintRequested() { m_histograms.fallbackFontPainted(m_period); }
 
+    bool isBlank() override { return m_period == BlockPeriod; }
+
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     PassRefPtr<SimpleFontData> createFontData(const FontDescription&) override;
     PassRefPtr<SimpleFontData> createLoadingFallbackFontData(const FontDescription&);
     void pruneTable();
 
 private:
     class FontLoadHistograms {
         DISALLOW_NEW();
@@ skipping 21 matching lines @@
     Member<CSSFontSelector> m_fontSelector;
     const FontDisplay m_display;
     DisplayPeriod m_period;
     FontLoadHistograms m_histograms;
     bool m_isInterventionTriggered;
 };
 
 } // namespace blink
 
 #endif