Change a parameter name from message_data to message based on a review comment from http://codere...

ppapi/cpp/instance.cc

 // 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.
 
 #include "ppapi/cpp/instance.h"
 
 #include "ppapi/c/dev/ppb_messaging_dev.h"
 #include "ppapi/c/dev/ppp_printing_dev.h"
 #include "ppapi/c/ppb_instance.h"
 #include "ppapi/cpp/common.h"
@@ skipping 48 matching lines @@
 
 
 bool Instance::HandleDocumentLoad(const URLLoader& /*url_loader*/) {
   return false;
 }
 
 bool Instance::HandleInputEvent(const PP_InputEvent& /*event*/) {
   return false;
 }
 
-void Instance::HandleMessage(const Var& /*message_data*/) {
+void Instance::HandleMessage(const Var& /*message*/) {
   return;
 }
 
 Var Instance::GetInstanceObject() {
   return Var();
 }
 
 Var Instance::GetSelectedText(bool /* html */) {
   return Var();
 }
@@ skipping 85 matching lines @@
   if (!that)
     return NULL;
   InterfaceNameToObjectMap::iterator found =
       that->interface_name_to_objects_.find(interface_name);
   if (found == that->interface_name_to_objects_.end())
     return NULL;
   return found->second;
 }
 
 }  // namespace pp