Add version-specific defines for each C interface.

ppapi/c/dev/ppb_widget_dev.h

 /* Copyright (c) 2010 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef PPAPI_C_DEV_PPB_WIDGET_DEV_H_
 #define PPAPI_C_DEV_PPB_WIDGET_DEV_H_
 
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_resource.h"
 
 struct PP_Rect;
 struct PP_InputEvent;
 
-#define PPB_WIDGET_DEV_INTERFACE "PPB_Widget(Dev);0.2"
+#define PPB_WIDGET_DEV_INTERFACE_0_2 "PPB_Widget(Dev);0.2"
+#define PPB_WIDGET_DEV_INTERFACE PPB_WIDGET_DEV_INTERFACE_0_2
 
 // The interface for reusing browser widgets.
 struct PPB_Widget_Dev {
   // Returns PP_TRUE if the given resource is a Widget. Returns PP_FALSE if the
   // resource is invalid or some type other than an Widget.
   PP_Bool (*IsWidget)(PP_Resource resource);
 
   // Paint the given rectangle of the widget into the given image.
   // Returns PP_TRUE on success, PP_FALSE on failure
   PP_Bool (*Paint)(PP_Resource widget,
                    const struct PP_Rect* rect,
                    PP_Resource image);
 
   // Pass in an event to a widget.  It'll return PP_TRUE if the event was
   // consumed.
   PP_Bool (*HandleEvent)(PP_Resource widget,
                          const struct PP_InputEvent* event);
 
   // Get/set the location of the widget.
   PP_Bool (*GetLocation)(PP_Resource widget,
                          struct PP_Rect* location);
 
   void (*SetLocation)(PP_Resource widget,
                       const struct PP_Rect* location);
 };
 
 #endif  /* PPAPI_C_DEV_PPB_WIDGET_DEV_H_ */