Add support for runtime fall-back from o3d to o2d.

core/cross/cairo/renderer_cairo.cc

 /*
  * Copyright 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 23 matching lines @@
 #include "core/cross/cairo/renderer_cairo.h"
 #include <cairo-xlib.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "core/cross/cairo/layer.h"
 #include "core/cross/cairo/texture_cairo.h"
 
 namespace o3d {
 
+// This is a factory function for creating 2D Renderer objects.
+Renderer* Renderer::Create2DRenderer(ServiceLocator* service_locator) {
+  return o2d::RendererCairo::CreateDefault(service_locator);
+}
+
 namespace o2d {
 
 RendererCairo::RendererCairo(ServiceLocator* service_locator)
     : Renderer(service_locator), display_(NULL), main_surface_(NULL) {
   // Don't need to do anything.
 }
 
 RendererCairo::~RendererCairo() {
   Destroy();
 }
@@ skipping 404 matching lines @@
   NOTIMPLEMENTED();
 }
 
 void RendererCairo::PopRenderStates() {
   NOTIMPLEMENTED();
 }
 
 }  // namespace o2d
 
 }  // namespace o3d