This CL adds client.toDataURL which gets the contents...

core/cross/renderer.h

 /*
  * Copyright 2009, 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 346 matching lines @@
   // SetLostResourcesCallback a second time or if you call
   // ClearLostResourcesCallback.
   void ClearLostResourcesCallback();
 
   // Creates and returns a platform-specific RenderDepthStencilSurface object
   // for use as a depth-stencil render target.
   virtual RenderDepthStencilSurface::Ref CreateDepthStencilSurface(
       int width,
       int height) = 0;
 
-  // Saves a png screenshot.
-  // Returns true on success and false on failure.
-  virtual bool SaveScreen(const String& file_name) = 0;
+  // Returns the screen as a Bitmap. Will return a null reference on error.
+  virtual Bitmap::Ref TakeScreenshot() = 0;
 
   ServiceLocator* service_locator() const { return service_locator_; }
 
   // Returns the type of Param needed for a particular state.
   const ObjectBase::Class* GetStateParamType(const String& state_name) const;
 
   // Get the client area's width.
   int width() const {
     return width_;
   }
@@ skipping 264 matching lines @@
 
   // Removes the default states from their respective stacks.
   void RemoveDefaultStates();
 
   DISALLOW_COPY_AND_ASSIGN(Renderer);
 };
 
 }  // namespace o3d
 
 #endif  // O3D_CORE_CROSS_RENDERER_H_