Fix SHIFT+TAB order on GAIA login screens

chrome/browser/resources/gaia_auth_host/authenticator.js

 // Copyright 2014 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 src="saml_handler.js">
 
 /**
  * @fileoverview An UI component to authenciate to Chrome. The component hosts
  * IdP web pages in a webview. A client who is interested in monitoring
  * authentication events should pass a listener object of type
@@ skipping 167 matching lines @@
     this.authFlow = AuthFlow.DEFAULT;
     this.samlHandler_.reset();
   };
 
   /**
    * Loads the authenticator component with the given parameters.
    * @param {AuthMode} authMode Authorization mode.
    * @param {Object} data Parameters for the authorization flow.
    */
   Authenticator.prototype.load = function(authMode, data) {
+    this.authMode = authMode;
     this.clearCredentials_();
     this.loaded_ = false;
     this.idpOrigin_ = data.gaiaUrl || IDP_ORIGIN;
     this.continueUrl_ = data.continueUrl || CONTINUE_URL;
     this.continueUrlWithoutParams_ =
         this.continueUrl_.substring(0, this.continueUrl_.indexOf('?')) ||
         this.continueUrl_;
     this.isConstrainedWindow_ = data.constrained == '1';
     this.isNewGaiaFlowChromeOS = data.isNewGaiaFlowChromeOS;
     this.useEafe_ = data.useEafe || false;
@@ skipping 117 matching lines @@
     else
       history.replaceState({url: url}, '');
   };
 
   /**
    * Invoked when the sign-in page takes focus.
    * @param {object} e The focus event being triggered.
    * @private
    */
   Authenticator.prototype.onFocus_ = function(e) {
-    this.webview_.focus();
+    if (this.authMode == AuthMode.DESKTOP)
+      this.webview_.focus();
   };
 
   /**
    * Invoked when the history state is changed.
    * @param {object} e The popstate event being triggered.
    * @private
    */
   Authenticator.prototype.onPopState_ = function(e) {
     var state = e.state;
     if (state && state.url)
@@ skipping 349 matching lines @@
   Authenticator.AuthMode = AuthMode;
   Authenticator.SUPPORTED_PARAMS = SUPPORTED_PARAMS;
 
   return {
     // TODO(guohui, xiyuan): Rename GaiaAuthHost to Authenticator once the old
     // iframe-based flow is deprecated.
     GaiaAuthHost: Authenticator,
     Authenticator: Authenticator
   };
 });