Remove the NPAPI plugin from the webapp.

remoting/webapp/host_setup_dialog.js

 // Copyright (c) 2012 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.
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /**
@@ skipping 335 matching lines @@
   var that = this;
   /** @type {remoting.HostSetupFlow} */
   var flow = this.flow_;
 
   /** @param {remoting.Error} error */
   var onError = function(error) {
     flow.switchToErrorState(error);
     that.updateState_();
   };
 
-  /** @param {remoting.HostController.AsyncResult} asyncResult */
-  var onDone = function(asyncResult) {
-    if (asyncResult == remoting.HostController.AsyncResult.OK) {
-      that.hostController_.getLocalHostState(onHostState);
-    } else if (asyncResult == remoting.HostController.AsyncResult.CANCELLED) {
-      onError(remoting.Error.CANCELLED);
-    } else {
-      onError(remoting.Error.UNEXPECTED);
-    }
+  var onDone = function() {
+    that.hostController_.getLocalHostState(onHostState);
   };
 
   /** @param {remoting.HostController.State} state */
   var onHostState = function(state) {
     var installed =
         state != remoting.HostController.State.NOT_INSTALLED &&
         state != remoting.HostController.State.INSTALLING;
 
     if (installed) {
       that.flow_.switchToNextStep();
       that.updateState_();
     } else {
-      // For Mac/Linux, prompt the user again if the host is not installed.
-      if (navigator.platform != 'Win32') {
-        hostInstallDialog.tryAgain();
-      } else {
-        // For Windows, report an error in the unlikely case that
-        // HostController.installHost reports AsyncResult.OK but the host is not
-        // installed.
-        console.error('The chromoting host is not installed.');
-        onError(remoting.Error.UNEXPECTED);
-      }
+      // Prompt the user again if the host is not installed.
+      hostInstallDialog.tryAgain();
     }
   };
 
   /** @type {remoting.HostInstallDialog} */
   var hostInstallDialog = new remoting.HostInstallDialog();
-  hostInstallDialog.show(
-      this.hostController_.getDispatcher().getNpapiHost(), onDone, onError);
+  hostInstallDialog.show(onDone, onError);
 }
 
 /**
  * Registers and starts the host.
  */
 remoting.HostSetupDialog.prototype.startHost_ = function() {
   /** @type {remoting.HostSetupDialog} */
   var that = this;
   /** @type {remoting.HostSetupFlow} */
   var flow = this.flow_;
@@ skipping 162 matching lines @@
     var c = pin.charAt(i);
     if ((c < '0') || (c > '9')) {
       return false;
     }
   }
   return true;
 };
 
 /** @type {remoting.HostSetupDialog} */
 remoting.hostSetupDialog = null;