Switch from using 'nacl_main' to 'main' entry point

ports/agg-demo/drawing.cc

 // Copyright (c) 2009 The Native Client Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // NaCl Drawing demo
 //   Uses Anti-Grain Geometry open source rendering library to render using
 //   the Pepper Graphics2D interface and ppapi_simple.
 //
 //   See http://www.antigrain.com for more information on Anti-Grain Geometry
 
 #include <errno.h>
 #include <stdio.h>
 
 #include <agg-2.5/agg_basics.h>
 #include <agg-2.5/agg_conv_stroke.h>
 #include <agg-2.5/agg_conv_transform.h>
 #include <agg-2.5/agg_ellipse.h>
 #include <agg-2.5/agg_path_storage.h>
 #include <agg-2.5/agg_pixfmt_rgba.h>
 #include <agg-2.5/agg_rendering_buffer.h>
 #include <agg-2.5/agg_rasterizer_outline_aa.h>
 #include <agg-2.5/agg_rasterizer_scanline_aa.h>
 #include <agg-2.5/agg_renderer_scanline.h>
 #include <agg-2.5/agg_scanline_u.h>
 
 #include "ppapi_simple/ps_context_2d.h"
-#include "ppapi_simple/ps_main.h"
 
 
 // Drawing class holds information and functionality needed to render
 class DrawingDemo {
  public:
   DrawingDemo(); ~DrawingDemo();
   void Display();
   void Update();
   bool PumpEvents();
   void Run();
@@ skipping 118 matching lines @@
     Update();
     PSContext2DSwapBuffer(ps_context_);
     printf("Frame: %04d\b\b\b\b\b\b\b\b\b\b\b", i);
     fflush(stdout);
   }
 
   printf("\nDone\n");
 }
 
 
-int example_main(int argc, char **argv) {
+int main(int argc, char **argv) {
   DrawingDemo demo;
   demo.Run();
   return 0;
 }
-
-
-PPAPI_SIMPLE_REGISTER_MAIN(example_main);