MD Settings: label and describe a bunch of subpage/open-in-new buttons

chrome/browser/resources/settings/search_page/search_page.html

 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/md_select_css.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="../controls/extension_controlled_indicator.html">
 <link rel="import" href="../controls/settings_toggle_button.html">
 <link rel="import" href="../icons.html">
 <link rel="import" href="../i18n_setup.html">
@@ skipping 87 matching lines @@
             <div class="settings-box continuation indented">
               <iron-icon icon="settings:warning"></iron-icon>
               <div inner-h-t-m-l="[[hotwordInfo_.errorMessage]]"></div>
             </div>
           </template>
 
           <template is="dom-if" if="[[hotwordInfo_.historyEnabled]]">
             <div class="settings-box two-line continuation indented"
                 on-tap="onManageAudioHistoryTap_" actionable>
               <div class="start">
-                <div>
-                  [[i18n('searchOkGoogleAudioHistoryLabel',
-                  hotwordInfo_.userName)]]
-                </div>
-                <div class="secondary">
+                [[i18n('searchOkGoogleAudioHistoryLabel',
+                       hotwordInfo_.userName)]]
+                <div class="secondary" id="audioHistorySecondary">
                   $i18n{searchOkGoogleAudioHistorySubtext}
                 </div>
               </div>
-              <button class="icon-external" is="paper-icon-button-light">
-              </button>
+              <button class="icon-external" is="paper-icon-button-light"
+                  aria-label="[[i18n('searchOkGoogleAudioHistoryLabel',
+                                     hotwordInfo_.userName)]]"
+                  aria-describedby="audioHistorySecondary"></button>
             </div>
           </template>
         </template>
 
         <!-- Manage search engines -->
         <div id="subpage-trigger" class="settings-box two-line"
             on-tap="onManageSearchEnginesTap_" actionable>
           <div class="start">
             $i18n{searchEnginesManage}
-            <div class="secondary">
+            <div class="secondary" id="manageSearchEnginesSecondary">
               $i18n{searchEnginesManageDescription}
             </div>
           </div>
-          <button class="subpage-arrow" is="paper-icon-button-light"></button>
+          <button class="subpage-arrow" is="paper-icon-button-light"
+              aria-label="$i18n{searchEnginesManage}"
+              aria-describedby="manageSearchEnginesSecondary"></button>
         </div>
       </neon-animatable>
       <template is="dom-if" route-path="/searchEngines">
         <settings-subpage
             associated-control="[[$$('#subpage-trigger')]]"
             page-title="$i18n{searchEnginesManage}">
           <settings-search-engines-page></settings-search-engines-page>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="search_page.js"></script>
 </dom-module>