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

chrome/browser/resources/settings/printing_page/printing_page.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-icon-button/paper-icon-button-light.html">
 <link rel="import" href="cloud_printers.html">
 <link rel="import" href="../route.html">
 <link rel="import" href="../settings_page/settings_animated_pages.html">
 <link rel="import" href="../settings_page/settings_subpage.html">
 <link rel="import" href="../settings_shared_css.html">
 <if expr="chromeos">
 <link rel="import" href="cups_printer_details_page.html">
 <link rel="import" href="cups_printers.html">
 </if>
 
 <dom-module id="settings-printing-page">
   <template>
     <style include="settings-shared"></style>
     <settings-animated-pages id="pages" section="printing">
       <array-selector id="arraySelector" items="{{cupsPrinters}}"
           selected="{{detailPrinter_}}">
       </array-selector>
       <neon-animatable route-path="default">
 <if expr="chromeos">
         <template is="dom-if" if="[[showCupsPrintingFeatures_]]">
           <div id="cupsPrinters" class="settings-box first"
               on-tap="onTapCupsPrinters_" actionable>
-            <div class="start">
-              $i18n{cupsPrintersTitle}
-            </div>
-            <button class="subpage-arrow" is="paper-icon-button-light"></button>
+            <div class="start">$i18n{cupsPrintersTitle}</div>
+            <button class="subpage-arrow" is="paper-icon-button-light"
+                aria-label="$i18n{cupsPrintersTitle}"></button>
           </div>
         </template>
 </if>
         <div id="cloudPrinters" class="settings-box two-line"
             on-tap="onTapCloudPrinters_" actionable>
           <div class="start">
             $i18n{cloudPrintersTitle}
-            <div class="secondary">$i18n{cloudPrintersTitleDescription}</div>
+            <div class="secondary" id="cloudPrintersSecondary">
+              $i18n{cloudPrintersTitleDescription}
+            </div>
           </div>
-          <button class="subpage-arrow" is="paper-icon-button-light"></button>
+          <button class="subpage-arrow" is="paper-icon-button-light"
+              aria-label="$i18n{cloudPrintersTitle}"
+              aria-describedby="cloudPrintersSecondary"></button>
         </div>
       </neon-animatable>
 <if expr="chromeos">
       <template is="dom-if" if="[[showCupsPrintingFeatures_]]">
         <template is="dom-if" route-path="/cupsPrinters">
           <settings-subpage
               associated-control="[[$$('#cupsPrinters')]]"
               page-title="$i18n{cupsPrintersTitle}"
               search-label="$i18n{searchLabel}"
               search-term="{{searchTerm}}">
@@ skipping 16 matching lines @@
             associated-control="[[$$('#cloudPrinters')]]"
             page-title="$i18n{cloudPrintersTitle}">
           <settings-cloud-printers prefs="{{prefs}}">
           </settings-cloud-printers>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="printing_page.js"></script>
 </dom-module>