Manage WebGLRenderingContextBase's weak refs manually without Oilpan.

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

 /*
  * Copyright (C) 2009 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 6674 matching lines @@
 DEFINE_TRACE(WebGLRenderingContextBase::TextureUnitState)
 {
     visitor->trace(m_texture2DBinding);
     visitor->trace(m_textureCubeMapBinding);
     visitor->trace(m_texture3DBinding);
     visitor->trace(m_texture2DArrayBinding);
 }
 
 DEFINE_TRACE(WebGLRenderingContextBase)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_contextObjects);
+#endif
     visitor->trace(m_contextLostCallbackAdapter);
     visitor->trace(m_errorMessageCallbackAdapter);
     visitor->trace(m_boundArrayBuffer);
     visitor->trace(m_defaultVertexArrayObject);
     visitor->trace(m_boundVertexArrayObject);
     visitor->trace(m_vertexAttrib0Buffer);
     visitor->trace(m_currentProgram);
     visitor->trace(m_framebufferBinding);
     visitor->trace(m_renderbufferBinding);
     visitor->trace(m_valuebufferBinding);
@@ skipping 29 matching lines @@
 
     return totalBytesPerPixel;
 }
 
 DrawingBuffer* WebGLRenderingContextBase::drawingBuffer() const
 {
     return m_drawingBuffer.get();
 }
 
 } // namespace blink