MD-Settings: Adds an a11y label to most toggle buttons.

chrome/browser/resources/settings/a11y_page/a11y_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../settings_shared_css.html">
 
 <if expr="chromeos">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-toggle-button/paper-toggle-button.html">
 <link rel="import" href="manage_a11y_page.html">
 <link rel="import" href="../settings_page/settings_animated_pages.html">
 <link rel="import" href="../settings_page/settings_subpage.html">
 </if>
 
 <dom-module id="settings-a11y-page">
   <template>
     <style include="settings-shared"></style>
 <if expr="chromeos">
     <settings-animated-pages id="pages" current-route="{{currentRoute}}"
         section="a11y">
       <neon-animatable route-path="default">
         <div class="settings-box first">
-          <div class="start">$i18n{optionsInMenuLabel}</div>
+          <div id="optionsInMenuLabel" class="start">
+            $i18n{optionsInMenuLabel}
+          </div>
           <paper-toggle-button id="optionsInMenuToggle"
-              checked="{{prefs.settings.a11y.enable_menu.value}}">
+              checked="{{prefs.settings.a11y.enable_menu.value}}"
+              aria-labelledby="optionsInMenuLabel">
           </paper-toggle-button>
         </div>
         <template is="dom-if" if="[[!isGuest_]]">
           <div id="subpage-trigger" class="settings-box two-line"
               on-tap="onManageAccessibilityFeaturesTap_" actionable>
             <div class="start">
               $i18n{manageAccessibilityFeatures}
               <div class="secondary" id="themesSecondary">
                 $i18n{moreFeaturesLinkDescription}
               </div>
@@ skipping 27 matching lines @@
       </div>
       <button class="icon-external" is="paper-icon-button-light"
           aria-label="$i18n{moreFeaturesLink}"
           aria-describedby="moreFeaturesSecondary"></button>
     </div>
 </if>
 
   </template>
   <script src="a11y_page.js"></script>
 </dom-module>