Do not show "Just a sec" page if arc-loading page is shown.

chrome/browser/resources/chromeos/arc_support/background.js

 // Copyright 2016 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.
 
 /**
  * Chrome window that hosts UI. Only one window is allowed.
  * @type {chrome.app.window.AppWindow}
  */
 var appWindow = null;
 
@@ skipping 469 matching lines @@
  * 'none' hides all views.
  * @param {string} pageDivId id of divider of the page to show.
  */
 function showPage(pageDivId) {
   if (!appWindow) {
     return;
   }
 
   hideOverlay();
   var doc = appWindow.contentWindow.document;
-  var pages = doc.getElementsByClassName('section');
-  for (var i = 0; i < pages.length; i++) {
-    pages[i].hidden = pages[i].id != pageDivId;
+  // If the request is lso-loading and arc-loading page is currently shown,
+  // then we do not switch the view. This is because both pages are saying
+  // "operation in progress", and switching the page looks unwanted message
+  // change from users' point of view.
+  if (pageDivId != 'lso-loading' || doc.getElementById('arc-loading').hidden) {
+    var pages = doc.getElementsByClassName('section');
+    for (var i = 0; i < pages.length; i++) {
+      pages[i].hidden = pages[i].id != pageDivId;
+    }
   }
 
   if (pageDivId == 'lso-loading') {
     lsoView.src = 'https://accounts.google.com/o/oauth2/v2/auth?client_id=' +
                   '1070009224336-sdh77n7uot3oc99ais00jmuft6sk2fg9.apps.' +
                   'googleusercontent.com&response_type=code&redirect_uri=oob&' +
                   'scope=https://www.google.com/accounts/OAuthLogin&' +
                   'device_type=arc_plus_plus&device_id=' + currentDeviceId +
                   '&hl=' + navigator.language;
   }
@@ skipping 236 matching lines @@
       type: 'chrome',
       color: '#ffffff'
     },
     'innerBounds': {
       'width': INNER_WIDTH,
       'height': INNER_HEIGHT
     }
   };
   chrome.app.window.create('main.html', options, onWindowCreated);
 });