WebFonts: measure network loading time

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 52 matching lines @@
     public:
         FontLoadHistograms() : m_loadStartTime(0), m_blankPaintTime(0), m_isLongLimitExceeded(false) { }
         void loadStarted();
         void fallbackFontPainted(DisplayPeriod);
         void fontLoaded(bool isInterventionTriggered, bool isLoadedFromNetwork);
         void longLimitExceeded(bool isInterventionTriggered);
         void recordFallbackTime(const FontResource*);
         void recordRemoteFont(const FontResource*, bool isLoadedFromMemoryCache);
         bool hadBlankText() { return m_blankPaintTime; }
     private:
-        void recordLoadTimeHistogram(const FontResource*, int duration);
+        void recordLoadTimeHistogram(const FontResource*, int duration, bool isLoadedFromNetwork);

[kouhei (in TOK), 2016/09/02 03:22:20]

Can we have a enum for describing the source?
Looking at the below diff, we already have isLoadedFromMemoryCache which seems
to be opposite of this.

[Takashi Toyoshima, 2016/09/02 10:51:00]

Actually, it's not opposite of this since we have two other cases. But that
means enum is more preferable here.

Once concern is that the source couldn't be determined at a single timing, but
at multiple events. But I think we can manage it easily, and could reduce risks
to make mistakes.

         void recordInterventionResult(bool isTriggered, bool isLoadedFromNetwork);
         double m_loadStartTime;
         double m_blankPaintTime;
         bool m_isLongLimitExceeded;
     };
 
     void switchToSwapPeriod();
     void switchToFailurePeriod();
 
     Member<FontResource> m_font;
     Member<CSSFontSelector> m_fontSelector;
     const FontDisplay m_display;
     DisplayPeriod m_period;
     FontLoadHistograms m_histograms;
     bool m_isInterventionTriggered;
     bool m_isLoadedFromMemoryCache;
 };
 
 } // namespace blink
 
 #endif