Make FontFaceCache::version return unique number across all instances

third_party/WebKit/Source/core/css/FontFaceCache.h

 /*
  * Copyright (C) 2007, 2008, 2011 Apple Inc. All rights reserved.
  * 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 47 matching lines @@
 
   // FIXME: It's sort of weird that add/remove uses StyleRuleFontFace* as key,
   // but this function uses FontDescription/family pair.
   CSSSegmentedFontFace* get(const FontDescription&, const AtomicString& family);
 
   const HeapListHashSet<Member<FontFace>>& cssConnectedFontFaces() const {
     return m_cssConnectedFontFaces;
   }
 
   unsigned version() const { return m_version; }
-  void incrementVersion() { ++m_version; }
+  void incrementVersion();
 
   DECLARE_TRACE();
 
  private:
   using TraitsMap = HeapHashMap<unsigned, Member<CSSSegmentedFontFace>>;
   using FamilyToTraitsMap =
       HeapHashMap<String, Member<TraitsMap>, CaseFoldingHash>;
   using StyleRuleToFontFace =
       HeapHashMap<Member<const StyleRuleFontFace>, Member<FontFace>>;
   FamilyToTraitsMap m_fontFaces;
   FamilyToTraitsMap m_fonts;
   StyleRuleToFontFace m_styleRuleToFontFace;
   HeapListHashSet<Member<FontFace>> m_cssConnectedFontFaces;
 
   // FIXME: See if this could be ditched
   // Used to compare Font instances, and the usage seems suspect.
   unsigned m_version;
 };
 
 }  // namespace blink
 
 #endif