Fix navigation stops on Parental Controls page

Previously, there were 3 navigation stops for Parental Controls:
1) Title of the row, 2) sub-text, and 3) Set Up button. With this
change there are now two stops: 1) Title of the row with sub-text
as description, and 2) Set Up button with sub-text as description.


Bug: 1012565
Change-Id: I5ebe2afe3d8b43a0ad7e60aeffcc5ea35a28eaab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1912697Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Bailey Berro <baileyberro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714980}

chrome/browser/resources/settings/parental_controls_page/parental_controls_page.html

@@ -30,15 +30,16 @@
       </template>
       <template is="dom-if" if="[[!isChild_]]">
         <div class="start settings-box-text">
-          <div>
+          <div id="label" aria-describedby="sub-label">
             $i18n{parentalControlsPageTitle}
           </div>
-          <div class="secondary">
+          <div class="secondary" id="sub-label" aria-hidden="true">
             [[getSetupLabelText_(online_)]]
           </div>
         </div>
         <div class="separator"></div>
-        <cr-button on-click="handleSetupButtonClick_" disabled$="[[!online_]]">
+        <cr-button on-click="handleSetupButtonClick_" disabled$="[[!online_]]"
+            aria-describedby="sub-label">
           $i18n{parentalControlsSetUpButtonLabel}
         </cr-button>
       </template>