Oilpan: have CSSImageGeneratorValue use SelfKeepAlive<>.

Source/core/css/CSSImageGeneratorValue.cpp

 /*
  * Copyright (C) 2008 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 32 matching lines @@
 }
 
 void CSSImageGeneratorValue::addClient(LayoutObject* layoutObject, const IntSize& size)
 {
     ASSERT(layoutObject);
 #if !ENABLE(OILPAN)
     ref();
 #else
     if (m_clients.isEmpty()) {
         ASSERT(!m_keepAlive);
-        m_keepAlive = adoptPtr(new Persistent<CSSImageGeneratorValue>(this));
+        m_keepAlive = this;
     }
 #endif
 
     if (!size.isEmpty())
         m_sizes.add(size);
 
     LayoutObjectSizeCountMap::iterator it = m_clients.find(layoutObject);
     if (it == m_clients.end()) {
         m_clients.add(layoutObject, SizeAndCount(size, 1));
     } else {
@@ skipping 18 matching lines @@
     }
 
     if (!--sizeCount.count)
         m_clients.remove(layoutObject);
 
 #if !ENABLE(OILPAN)
     deref();
 #else
     if (m_clients.isEmpty()) {
         ASSERT(m_keepAlive);
-        m_keepAlive = nullptr;
+        m_keepAlive.clear();
     }
 #endif
 }
 
 Image* CSSImageGeneratorValue::getImage(LayoutObject* layoutObject, const IntSize& size)
 {
     LayoutObjectSizeCountMap::iterator it = m_clients.find(layoutObject);
     if (it != m_clients.end()) {
         SizeAndCount& sizeCount = it->value;
         IntSize oldSize = sizeCount.size;
@@ skipping 116 matching lines @@
         break;
     case RadialGradientClass:
         toCSSRadialGradientValue(this)->loadSubimages(document);
         break;
     default:
         ASSERT_NOT_REACHED();
     }
 }
 
 } // namespace blink