Allow DrawingBuffer to present to a bitmap.

Source/WebKit/chromium/tests/FakeWebGraphicsContext3D.h

 /*
  * Copyright (C) 2011 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:
  *
  * 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
@@ skipping 29 matching lines @@
     {
     }
 
     virtual bool makeContextCurrent() { return true; }
 
     virtual int width() { return 0; }
     virtual int height() { return 0; }
 
     virtual void reshape(int width, int height) { }
 
-    virtual bool readBackFramebuffer(unsigned char* pixels, size_t bufferSize, WebGLId framebuffer, int width, int height) { return false; }
-
     virtual void prepareTexture() { }
 
     virtual void postSubBufferCHROMIUM(int x, int y, int width, int height) { }
 
     virtual void synthesizeGLError(WGC3Denum) { }
 
     virtual bool isContextLost() { return false; }
 
     virtual void* mapBufferSubDataCHROMIUM(WGC3Denum target, WGC3Dintptr offset, WGC3Dsizeiptr size, WGC3Denum access) { return 0; }
     virtual void unmapBufferSubDataCHROMIUM(const void*) { }
@@ skipping 206 matching lines @@
     virtual void getQueryObjectuivEXT(WebGLId, GC3Denum, GC3Duint*) { }
 
 protected:
     unsigned m_nextTextureId;
     Attributes m_attrs;
 };
 
 } // namespace WebKit
 
 #endif // FakeWebGraphicsContext3D_h