WebFonts: classify memory cache hit case in WebFont.CacheHit metric

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

Index: third_party/WebKit/Source/core/css/RemoteFontFaceSource.cpp
diff --git a/third_party/WebKit/Source/core/css/RemoteFontFaceSource.cpp b/third_party/WebKit/Source/core/css/RemoteFontFaceSource.cpp
index 319e74e8478e12064bdb7a0f472acf66b752815c..9eaab89c8a1282f37cb7b23812587874a146c9bb 100644
--- a/third_party/WebKit/Source/core/css/RemoteFontFaceSource.cpp
+++ b/third_party/WebKit/Source/core/css/RemoteFontFaceSource.cpp
@@ -116,7 +116,7 @@ bool RemoteFontFaceSource::isValid() const
 
 void RemoteFontFaceSource::notifyFinished(Resource*)
 {
-    m_histograms.recordRemoteFont(m_font.get());
+    m_histograms.recordRemoteFont(m_font.get(), m_isLoadedFromMemoryCache);
     m_histograms.fontLoaded(m_isInterventionTriggered, !m_isLoadedFromMemoryCache && !m_font->url().protocolIsData() && !m_font->response().wasCached());
 
     m_font->ensureCustomFontData();
@@ -260,16 +260,17 @@ void RemoteFontFaceSource::FontLoadHistograms::recordFallbackTime(const FontReso
     m_blankPaintTime = -1;
 }
 
-void RemoteFontFaceSource::FontLoadHistograms::recordRemoteFont(const FontResource* font)
+void RemoteFontFaceSource::FontLoadHistograms::recordRemoteFont(const FontResource* font, bool isLoadedFromMemoryCache)
 {
     if (m_loadStartTime > 0 && font && !font->isLoading()) {
         int duration = static_cast<int>(currentTimeMS() - m_loadStartTime);
         recordLoadTimeHistogram(font, duration);
         m_loadStartTime = -1;
 
-        enum { Miss, Hit, DataUrl, CacheHitEnumMax };
+        enum { Miss, DiskHit, DataUrl, MemoryHit, CacheHitEnumMax };
         int histogramValue = font->url().protocolIsData() ? DataUrl

[Takashi Toyoshima, 2016/08/31 05:38:09]

From a chat with yhirano, I should check isLoadedFromMemoryCache first because
wasCached() could be both true and false even if isLoadedFromMemoryCache is
true. wasCached() just returns cached information about the disk cache for
memory cache hit cases.

-            : font->response().wasCached() ? Hit
+            : font->response().wasCached() ? DiskHit
+            : isLoadedFromMemoryCache ? MemoryHit

[tkent, 2016/08/31 05:21:30]

Why don't you refer to m_isLoadedFromMemoryCache directly?

[Takashi Toyoshima, 2016/08/31 05:31:50]

Because here is inside an inner class, and this instance is instantiated without
a reference to the parent, RemoteFontFaceSource class instance.

[tkent, 2016/08/31 06:21:33]

I wasn't aware of it.  Got it.

             : Miss;
         DEFINE_STATIC_LOCAL(EnumerationHistogram, cacheHitHistogram, ("WebFont.CacheHit", CacheHitEnumMax));
         cacheHitHistogram.count(histogramValue);