Webfonts should not block load event for more than one frame

Source/core/css/FontLoader.cpp

 // 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.
 
 #include "config.h"
 #include "core/css/FontLoader.h"
 
 #include "core/css/CSSFontSelector.h"
 #include "core/fetch/FontResource.h"
 #include "core/fetch/ResourceFetcher.h"
 
 namespace blink {
 
 FontLoader::FontLoader(CSSFontSelector* fontSelector, ResourceFetcher* resourceFetcher)
     : m_beginLoadingTimer(this, &FontLoader::beginLoadTimerFired)
     , m_fontSelector(fontSelector)
     , m_resourceFetcher(resourceFetcher)
 {
 }
 
 FontLoader::~FontLoader()
 {
 #if ENABLE(OILPAN)
     if (!m_resourceFetcher) {
         ASSERT(m_fontsToBeginLoading.isEmpty());
         return;
     }
     m_beginLoadingTimer.stop();
-
-    // When the m_fontsToBeginLoading vector is destroyed it will decrement the
-    // request counts on the ResourceFetcher for all the fonts that were pending
-    // at the time the FontLoader dies.
+    // This will decrement the request counts on the ResourceFetcher for all the
+    // fonts that were pending at the time the FontLoader dies.
+    clearPendingFonts();
 #endif
 }
 
 void FontLoader::addFontToBeginLoading(FontResource* fontResource)
 {
-    if (!m_resourceFetcher || !fontResource->stillNeedsLoad())
+    if (!m_resourceFetcher || !fontResource->stillNeedsLoad() || fontResource->loadScheduled())
         return;
 
     m_fontsToBeginLoading.append(
         std::make_pair(fontResource, ResourceLoader::RequestCountTracker(m_resourceFetcher, fontResource)));
+    fontResource->setLoadScheduled(true);
     if (!m_beginLoadingTimer.isActive())
         m_beginLoadingTimer.startOneShot(0, FROM_HERE);
 }
 
 void FontLoader::beginLoadTimerFired(Timer<blink::FontLoader>*)
 {
     loadPendingFonts();
 }
 
 void FontLoader::loadPendingFonts()
@@ skipping 20 matching lines @@
 
 #if !ENABLE(OILPAN)
 void FontLoader::clearResourceFetcherAndFontSelector()
 {
     if (!m_resourceFetcher) {
         ASSERT(m_fontsToBeginLoading.isEmpty());
         return;
     }
 
     m_beginLoadingTimer.stop();
-    m_fontsToBeginLoading.clear();
+    clearPendingFonts();
     m_resourceFetcher = nullptr;
     m_fontSelector = nullptr;
 }
 #endif
 
+void FontLoader::clearPendingFonts()
+{
+    for (FontsToLoadVector::iterator it = m_fontsToBeginLoading.begin(); it != m_fontsToBeginLoading.end(); ++it)
+        it->first->setLoadScheduled(false);
+    m_fontsToBeginLoading.clear();
+}
+
 void FontLoader::trace(Visitor* visitor)
 {
     visitor->trace(m_resourceFetcher);
     visitor->trace(m_fontSelector);
 }
 
 } // namespace blink