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

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

Index: third_party/WebKit/Source/core/css/FontFace.cpp
diff --git a/third_party/WebKit/Source/core/css/FontFace.cpp b/third_party/WebKit/Source/core/css/FontFace.cpp
index 59b526bbd633ddfb8043f35a64a24294a1792013..84645e2cdf7ae786797e0da1896432213e9521aa 100644
--- a/third_party/WebKit/Source/core/css/FontFace.cpp
+++ b/third_party/WebKit/Source/core/css/FontFace.cpp
@@ -533,6 +533,11 @@ FontTraits FontFace::traits() const
     return FontTraits(style, variant, weight, stretch);
 }
 
+bool FontFace::isBlank() const
+{
+    return m_status == Loading && m_charCount > 200 && m_cssFontFace->isBlank();
+}
+
 static FontDisplay CSSValueToFontDisplay(CSSValue* value)
 {
     if (value && value->isPrimitiveValue()) {
@@ -624,6 +629,21 @@ void FontFace::initCSSFontFace(const unsigned char* data, size_t size)
     m_cssFontFace->addSource(source);
 }
 
+bool FontFace::willUseFontData(const FontDescription& fontDescription, const String& text)
+{
+    if (m_status != Loaded) {
+        m_charCount += text.length();
+        // if (m_cssFontFace->isBlank())
+        //     fprintf(stderr, "%s %u %u\n", m_family.getString().ascii().data(), length, m_charCount);
+    }
+    if (loadStatus() != Unloaded)
+        return true;
+    if (cssFontFace()->maybeScheduleFontLoad(fontDescription, text.characterStartingAt(0))) {
+        return true;
+    }
+    return false;
+}
+
 DEFINE_TRACE(FontFace)
 {
     visitor->trace(m_style);