Convert URLLoader to the new proxy design

ppapi/thunk/ppb_url_loader_thunk.cc

Index: ppapi/thunk/ppb_url_loader_thunk.cc
diff --git a/ppapi/thunk/ppb_url_loader_thunk.cc b/ppapi/thunk/ppb_url_loader_thunk.cc
index 23113cd1ce7aff0d65276b46e71df536cabc3db1..f472234ee13d068c2e4057babe2fa4dc623bd370 100644
--- a/ppapi/thunk/ppb_url_loader_thunk.cc
+++ b/ppapi/thunk/ppb_url_loader_thunk.cc
@@ -111,13 +111,6 @@ void GrantUniversalAccess(PP_Resource loader) {
     enter.object()->GrantUniversalAccess();
 }
 
-void SetStatusCallback(PP_Resource loader,
-                       PP_URLLoaderTrusted_StatusCallback cb) {
-  EnterURLLoader enter(loader, true);
-  if (enter.succeeded())
-    enter.object()->SetStatusCallback(cb);
-}
-
 const PPB_URLLoader g_ppb_urlloader_thunk = {
   &Create,
   &IsURLLoader,
@@ -133,7 +126,7 @@ const PPB_URLLoader g_ppb_urlloader_thunk = {
 
 const PPB_URLLoaderTrusted g_ppb_urlloader_trusted_thunk = {
   &GrantUniversalAccess,
-  &SetStatusCallback
+  NULL  // TODO(brettw) remove SetStatusCallback from the header.
 };
 
 }  // namespace