[chrome.displaySource] further implementation of call completion callbacks

extensions/renderer/resources/display_source_custom_bindings.js

 // Copyright 2015 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.
 
 // Custom binding for the Display Source API.
 
 var binding = require('binding').Binding.create('displaySource');
 var chrome = requireNative('chrome').GetChrome();
 var lastError = require('lastError');
 var natives = requireNative('display_source');
 var logging = requireNative('logging');
 
 var callbacksInfo = {};
 
 function callbackWrapper(callback, method, message) {
   if (callback == undefined)
     return;
 
   try {
     if (message !== null)
-      lastError.set('displaySource.startSession', message, null, chrome);
+      lastError.set(method, message, null, chrome);
     callback();
   } finally {
     lastError.clear(chrome);
   }
 }
 
 function callCompletionCallback(callbackId, error_message) {
   try {
     var callbackInfo = callbacksInfo[callbackId];
     logging.DCHECK(callbackInfo != null);
     callbackWrapper(callbackInfo.callback, callbackInfo.method, error_message);
   } finally {
     delete callbacksInfo[callbackId];
   }
 }
 
 binding.registerCustomHook(function(bindingsAPI, extensionId) {
   var apiFunctions = bindingsAPI.apiFunctions;
   apiFunctions.setHandleRequest(
       'startSession', function(sessionInfo, callback) {
         try {
-          var callId = natives.StartSession(sessionInfo, callbackWrapper);
+          var callId = natives.StartSession(sessionInfo);
           callbacksInfo[callId] = {
             callback: callback,
             method: 'displaySource.startSession'
           };
         } catch (e) {
           callbackWrapper(callback, 'displaySource.startSession', e.message);
         }
       });
   apiFunctions.setHandleRequest(
       'terminateSession', function(sink_id, callback) {
         try {
-          var callId = natives.TerminateSession(sink_id, callbackWrapper);
+          var callId = natives.TerminateSession(sink_id);
           callbacksInfo[callId] = {
             callback: callback,
             method: 'displaySource.terminateSession'
           };
         } catch (e) {
           callbackWrapper(
               callback, 'displaySource.terminateSession', e.message);
         }
       });
 });
 
 exports.$set('binding', binding.generate());
 // Called by C++.
 exports.$set('callCompletionCallback', callCompletionCallback);