Make HarfBuzzFace release SimpleFontData.

third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzFace.h

 /*
  * Copyright (c) 2012 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 52 matching lines @@
   hb_font_t* getScaledFont(PassRefPtr<UnicodeRangeSet> = nullptr) const;
 
  private:
   HarfBuzzFace(FontPlatformData*, uint64_t);
 
   hb_face_t* createFace();
   void prepareHarfBuzzFontData();
 
   FontPlatformData* m_platformData;
   uint64_t m_uniqueID;
+  mutable class SimpleFontData* m_simpleFontData;

[drott, 2016/10/11 11:40:44]

Because of the way the caching works in this class, I'd prefer to avoid
additional storage in HarfBuzzFace itself for pointers to SimpleFontData or
FontPlatformData. As much as possible should be in HarfBuzzFontData since these
we have a lot fewer of those. SimpleFontData objects actually keep a copy of
FontPlatformData objects, so this would be redundantly storing the same
FontPlatformData inside the m_simpleFontData.

A longer term consideration might be, whether we should hang HarfBuzzFace off of
SimpleFontData or make the main m_platformData maybe a m_simpleFontData.

   hb_font_t* m_unscaledFont;
   HarfBuzzFontData* m_harfBuzzFontData;
 };
 
 }  // namespace blink
 
 #endif  // HarfBuzzFace_h