MD Settings: Listen to the Enter key in the Add User ChromeOS dialog.

chrome/browser/resources/settings/people_page/users_add_user_dialog.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.
 
 /**
  * @fileoverview
  * 'settings-users-add-user-dialog' is the dialog shown for adding new allowed
  * users to a ChromeOS device.
  */
 (function() {
@@ skipping 39 matching lines @@
     var input = this.$.addUserInput.value;
     var valid = NAME_ONLY_REGEX.test(input) || EMAIL_REGEX.test(input);
 
     this.$.add.disabled = !valid;
     this.$.addUserInput.invalid = !valid;
     return valid;
   },
 
   /** @private */
   addUser_: function() {
-    assert(this.validate_());
+    // May be submitted by the Enter key even if the input value is invalid.
+    if (!this.validate_())
+      return;
 
     var input = this.$.addUserInput.value;
 
     var nameOnlyMatches = NAME_ONLY_REGEX.exec(input);
     var userEmail;
     if (nameOnlyMatches) {
       userEmail = nameOnlyMatches[1] + '@gmail.com';
     } else {
       var emailMatches = EMAIL_REGEX.exec(input);
       // Assuming the input validated, one of these two must match.
       assert(emailMatches);
       userEmail = emailMatches[1] + '@' + emailMatches[2];
     }
 
     chrome.usersPrivate.addWhitelistedUser(
         userEmail,
         /* callback */ function(success) {});
     this.$.addUserInput.value = '';
     this.$.dialog.close();
   },
 });
 
 })();