Introduce typeface cache in blink::FontCache

third_party/WebKit/Source/platform/fonts/FontDataCache.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 42 matching lines @@
     }
 
     static const bool safeToCompareToEmptyOrDeleted = true;
 };
 
 struct FontDataCacheKeyTraits : WTF::GenericHashTraits<FontPlatformData> {
     STATIC_ONLY(FontDataCacheKeyTraits);
     static const bool emptyValueIsZero = true;
     static const FontPlatformData& emptyValue()
     {
-        DEFINE_STATIC_LOCAL(FontPlatformData, key, (0.f, false, false));
+        DEFINE_STATIC_LOCAL(FontPlatformData, key, (false, false));
         return key;
     }
     static void constructDeletedValue(FontPlatformData& slot, bool)
     {
         new (NotNull, &slot) FontPlatformData(WTF::HashTableDeletedValue);
     }
     static bool isDeletedValue(const FontPlatformData& value)
     {
         return value.isHashTableDeletedValue();
     }
 };
 
 class FontDataCache {
     USING_FAST_MALLOC(FontDataCache);
     WTF_MAKE_NONCOPYABLE(FontDataCache);
 public:
     FontDataCache() { }
 
-    PassRefPtr<SimpleFontData> get(const FontPlatformData*, ShouldRetain = Retain);
+    PassRefPtr<SimpleFontData> get(const FontPlatformData*, float fontSize, ShouldRetain = Retain);
     bool contains(const FontPlatformData*) const;
     void release(const SimpleFontData*);
 
     // This is used by FontVerticalDataCache to mark all items with vertical data
     // that are currently in cache as "in cache", which is later used to sweep the FontVerticalDataCache.
     void markAllVerticalData();
 
     // Purges items in FontDataCache according to provided severity.
     // Returns true if any removal of cache items actually occurred.
     bool purge(PurgeSeverity);
 
 private:
     bool purgeLeastRecentlyUsed(int count);
 
-    typedef HashMap<FontPlatformData, std::pair<RefPtr<SimpleFontData>, unsigned>, FontDataCacheKeyHash, FontDataCacheKeyTraits> Cache;
+    typedef HashMap<float, std::pair<RefPtr<SimpleFontData>, unsigned>> InnerCache;
+    typedef HashMap<FontPlatformData, InnerCache, FontDataCacheKeyHash, FontDataCacheKeyTraits> Cache;
     Cache m_cache;
     ListHashSet<RefPtr<SimpleFontData>> m_inactiveFontData;
 };
 
 } // namespace blink
 
 #endif