Make HarfBuzzFace release SimpleFontData.

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

 /*
  * 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 66 matching lines @@
 
 // struct to carry user-pointer data for hb_font_t callback functions.
 struct HarfBuzzFontData {
   USING_FAST_MALLOC(HarfBuzzFontData);
   WTF_MAKE_NONCOPYABLE(HarfBuzzFontData);
 
  public:
   HarfBuzzFontData()
       : m_paint(), m_simpleFontData(nullptr), m_rangeSet(nullptr) {}
 
+  ~HarfBuzzFontData() {
+    if (m_simpleFontData)
+      FontCache::fontCache()->releaseFontData(m_simpleFontData);
+  }
+
+  void updateSimpleFontData(FontPlatformData* platformData) {
+    SimpleFontData* simpleFontData =
+        FontCache::fontCache()
+            ->fontDataFromFontPlatformData(platformData)
+            .get();
+    if (m_simpleFontData)

[drott, 2016/10/13 07:28:34]

I think in the else case we need to release the new simpleFontData, don't we?

Or, alternatively, compare 
m_simpleFontData->platformData().size() to platformData.size() and only lookup a
new one from the cache if they differ. If all LayoutTests pass after that, this
should be fine, too.

[jb, 2016/10/13 07:53:47]

I think you misread the code. I always release the old one. If there is no
change, then releasing the old one has the same effect as releasing the new one,
so the counter is balanced either way.

[drott, 2016/10/13 08:06:29]

True, sorry.

+      FontCache::fontCache()->releaseFontData(m_simpleFontData);
+    m_simpleFontData = simpleFontData;
+  }
+
   SkPaint m_paint;
   SimpleFontData* m_simpleFontData;
   RefPtr<UnicodeRangeSet> m_rangeSet;
 };
 
 // Though we have FontCache class, which provides the cache mechanism for
 // WebKit's font objects, we also need additional caching layer for HarfBuzz to
 // reduce the number of hb_font_t objects created. Without it, we would create
 // an hb_font_t object for every FontPlatformData object. But insted, we only
 // need one for each unique SkTypeface.
@@ skipping 266 matching lines @@
   hb_font_set_funcs(unscaledFont, harfBuzzSkiaGetFontFuncs(),
                     cacheEntry->hbFontData(), nullptr);
   return cacheEntry;
 }
 
 hb_font_t* HarfBuzzFace::getScaledFont(
     PassRefPtr<UnicodeRangeSet> rangeSet) const {
   m_platformData->setupPaint(&m_harfBuzzFontData->m_paint);
   m_harfBuzzFontData->m_paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
   m_harfBuzzFontData->m_rangeSet = rangeSet;
-  m_harfBuzzFontData->m_simpleFontData =
-      FontCache::fontCache()
-          ->fontDataFromFontPlatformData(m_platformData)
-          .get();
+  m_harfBuzzFontData->updateSimpleFontData(m_platformData);
   ASSERT(m_harfBuzzFontData->m_simpleFontData);
   int scale = SkiaScalarToHarfBuzzPosition(m_platformData->size());
   hb_font_set_scale(m_unscaledFont, scale, scale);
   return m_unscaledFont;
 }
 
 }  // namespace blink