Use a FontPlatformData pointer for FontDataCache's key

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 24 matching lines @@
 #include "platform/fonts/FontPlatformData.h"
 #include "wtf/HashMap.h"
 #include "wtf/ListHashSet.h"
 
 namespace blink {
 
 class SimpleFontData;
 
 struct FontDataCacheKeyHash {
     STATIC_ONLY(FontDataCacheKeyHash);
-    static unsigned hash(const FontPlatformData& platformData)
+    static unsigned hash(const FontPlatformData* platformData)
     {
-        return platformData.hash();
+        return platformData->hash();
     }
 
-    static bool equal(const FontPlatformData& a, const FontPlatformData& b)
+    static bool equal(const FontPlatformData* a, const FontPlatformData* b)
     {
-        return a == b;
+        const FontPlatformData* emptyValue = reinterpret_cast<FontPlatformData*>(-1);
+
+        if (a == emptyValue)

[eae, 2016/06/06 17:26:53]

What's the difference between emptyValue (-1) and null?

+            return b == emptyValue;
+        if (b == emptyValue)
+            return a == emptyValue;
+
+        if (!a || !b)
+            return a == b;
+
+        CHECK(a && b);
+
+        return *a == *b;
     }
 
     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));
-        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);
     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<const FontPlatformData*, std::pair<RefPtr<SimpleFontData>, unsigned>, FontDataCacheKeyHash> Cache;
     Cache m_cache;
     ListHashSet<RefPtr<SimpleFontData>> m_inactiveFontData;
 };
 
 } // namespace blink
 
 #endif