[Multi Profile] Don't allow the user to choose an empty profile name.

chrome/browser/resources/options/manage_profile_overlay.css

 /* Copyright (c) 2011 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.
  */
 
 #manage-profile-overlay {
   width: 500px;
 }
 
 .profile-icon-grid-item {
@@ skipping 30 matching lines @@
 
 #manage-profile-name-label {
   -webkit-margin-end: 20px;
 }
 
 #manage-profile-name {
   -webkit-box-flex: 1;
   display: block;
 }
 
-#manage-profile-duplicate-name-error {
+#manage-profile-name-error {
   -webkit-transition: max-height 0.2s, padding 0.2s;
   background-color: #eeb939;
   border-radius: 4px;
   font-weight: bold;
   margin-left: auto;
   margin-right: auto;
   max-height: 50px;
   overflow: hidden;
   padding: 1px 10px;
   text-align: center;
   width: 80%;
 }
 
-#manage-profile-duplicate-name-error.hiding {
+#manage-profile-name-error.hiding {
   max-height: 0;
   padding: 0 10px;
 }
 
 #manage-profile-icon-grid {
   background-color: rgba(255, 255, 255, 0.75);
   border: 1px solid rgba(0, 0, 0, 0.3);
   padding: 2px;
 }