Revert 106717 - Revert 106677 (caused several PPAPI test timeouts, see http://crbug.com/101154)

ppapi/proxy/interface_proxy.cc

 // Copyright (c) 2011 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.
 
 #include "ppapi/proxy/interface_proxy.h"
 
 #include "base/logging.h"
 #include "ppapi/proxy/dispatcher.h"
 
 namespace ppapi {
 namespace proxy {
 
 InterfaceProxy::InterfaceProxy(Dispatcher* dispatcher)
     : dispatcher_(dispatcher) {
 }
 
 InterfaceProxy::~InterfaceProxy() {
 }
 
 bool InterfaceProxy::Send(IPC::Message* msg) {
   return dispatcher_->Send(msg);
 }
 
-uint32 InterfaceProxy::SendCallback(PP_CompletionCallback callback) {
-  return dispatcher_->callback_tracker().SendCallback(callback);
-}
-
-PP_CompletionCallback InterfaceProxy::ReceiveCallback(
-    uint32 serialized_callback) {
-  return dispatcher_->callback_tracker().ReceiveCallback(serialized_callback);
-}
-
 }  // namespace proxy
 }  // namespace ppapi