Oilpan: Remove most WillBe types from the code base

third_party/WebKit/Source/platform/graphics/ImageObserver.h

 /*
  * Copyright (C) 2004, 2005, 2006 Apple Computer, 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 18 matching lines @@
 #include "platform/PlatformExport.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class Image;
 class IntRect;
 
 // Interface for notification about changes to an image, including decoding,
 // drawing, and animating.
-class PLATFORM_EXPORT ImageObserver : public WillBeGarbageCollectedMixin {
+class PLATFORM_EXPORT ImageObserver : public GarbageCollectedMixin {
 protected:
     virtual ~ImageObserver();
 public:
     virtual void decodedSizeChanged(const Image*, int delta) = 0;
     virtual void didDraw(const Image*) = 0;
 
     virtual bool shouldPauseAnimation(const Image*) = 0;
     virtual void animationAdvanced(const Image*) = 0;
 
     virtual void changedInRect(const Image*, const IntRect&) = 0;
 
     DEFINE_INLINE_VIRTUAL_TRACE() { }
 };
 
 } // namespace blink
 
 #endif