Update Source/platform/ to assume Oilpan only.

third_party/WebKit/Source/platform/graphics/filters/SourceAlpha.h

 /*
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #ifndef SourceAlpha_h
 #define SourceAlpha_h
 
 #include "platform/graphics/filters/FilterEffect.h"
 
 namespace blink {
 
 class PLATFORM_EXPORT SourceAlpha final : public FilterEffect {
 public:
-    static RawPtr<SourceAlpha> create(FilterEffect*);
+    static SourceAlpha* create(FilterEffect*);
 
     FloatRect determineAbsolutePaintRect(const FloatRect& requestedRect) override;
 
     FilterEffectType getFilterEffectType() const override { return FilterEffectTypeSourceInput; }
 
     TextStream& externalRepresentation(TextStream&, int indention) const override;
     PassRefPtr<SkImageFilter> createImageFilter(SkiaImageFilterBuilder&) override;
 
 private:
     explicit SourceAlpha(FilterEffect*);
 };
 
 } // namespace blink
 
 #endif // SourceAlpha_h