Oobe: update aria-label for user creation screen in add person flow

Bug: 1127546
Change-Id: Ib4797dc6d8f2b28c15c3b55fb1a122d1027d999f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2416502
Commit-Queue: Yunke Zhou <yunkez@google.com>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808382}

chrome/browser/resources/chromeos/login/user_creation.html

@@ -56,7 +56,7 @@ found in the LICENSE file. -->
     </style>
     <oobe-dialog id="userCreationDialog" role="dialog" has-buttons
         title-key="[[titleKey_]]" subtitle-key="[[subtitleKey_]]"
-        aria-label$="[[i18nDynamic(locale, 'userCreationTitle')]]"
+        aria-label$="[[i18nDynamic(locale, titleKey_)]]"
         for-step="create">
       <hd-iron-icon icon1x="oobe-32:googleg" icon2x="oobe-64:googleg"
         slot="oobe-icon">

chrome/browser/resources/chromeos/login/user_creation.js

@@ -72,12 +72,12 @@ Polymer({
 
     titleKey_: {
       type: String,
-      value: '',
+      value: 'userCreationTitle',
     },
 
     subtitleKey_: {
       type: String,
-      value: '',
+      value: 'userCreationSubtitle',
     },
 
   },