Convert URLLoader to the new proxy design

ppapi/c/private/ppb_proxy_private.h

Index: ppapi/c/private/ppb_proxy_private.h
diff --git a/ppapi/c/private/ppb_proxy_private.h b/ppapi/c/private/ppb_proxy_private.h
index eac3f572a031b1a76b5d2c430a28dbc845f0a3af..b185c2c4f70218cdbf346dde67bb9d99476f8af3 100644
--- a/ppapi/c/private/ppb_proxy_private.h
+++ b/ppapi/c/private/ppb_proxy_private.h
@@ -10,7 +10,7 @@
 #include "ppapi/c/pp_module.h"
 #include "ppapi/c/pp_resource.h"
 
-#define PPB_PROXY_PRIVATE_INTERFACE "PPB_Proxy_Private;5"
+#define PPB_PROXY_PRIVATE_INTERFACE "PPB_Proxy_Private;6"
 
 // Exposes functions needed by the out-of-process proxy to call into the
 // renderer PPAPI implementation.
@@ -34,11 +34,6 @@ struct PPB_Proxy_Private {
       PP_Module module,
       PP_Bool (*is_seen)(PP_Module, PP_Instance));
 
-  // Returns the number of bytes synchronously readable out of the URLLoader's
-  // buffer. Returns 0 on failure or if the url loader doesn't have any data
-  // now.
-  int32_t (*GetURLLoaderBufferedBytes)(PP_Resource url_loader);
-
   // Allows adding additional refcounts to the PluginModule that owns the
   // proxy dispatcher (and all interface proxies). For every AddRef call
   // there must be a corresponding release call.