This fixes a number of things that are warnings in the Mac compiler....

core/cross/bitmap.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 389 matching lines @@
 
  private:
   friend class IClassManager;
   static ObjectBase::Ref Create(ServiceLocator* service_locator);
 
   // pointer to the raw bitmap data
   scoped_array<uint8> image_data_;
   // format of the texture this is meant to represent.
   Texture::Format format_;
   // width of the bitmap in pixels.
-  unsigned int width_;
+  int width_;
   // height of the bitmap in pixels.
-  unsigned int height_;
+  int height_;
   // number of mipmap levels in this texture.
   unsigned int num_mipmaps_;
   // is this cube-map data
   bool is_cubemap_;
 
   // utility function used in AdjustDrawImageBoundary.
   // It adjusts start point and related measures
   // for a specific dimension.
   // Parameter:
   //   src_a: the coordinate which is negative.
   //   dest_a: same coordinate in the other image.
   //   src_length: length measure of source image to draw.
   //   dest_length: length measure of dest image to draw.
   //   src_bmp_length: length measure of src image.
   // Returns:
   //   true if adjust is successful.
   static bool AdjustDrawImageBoundHelper(int* src_a, int* dest_a,
                                          int* src_length, int* dest_length,
                                          int src_bmp_length);
 
   O3D_DECL_CLASS(Bitmap, ParamObject);
   DISALLOW_COPY_AND_ASSIGN(Bitmap);
 };
 
 }  // namespace o3d
 
 #endif  // O3D_CORE_CROSS_BITMAP_H_