A11y setting: mono audio UI

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-button/paper-button.html">
 <if expr="chromeos">
 <link rel="import" href="chrome://md-settings/controls/settings_checkbox.html">
 </if>
 <link rel="import" href="chrome://md-settings/settings_shared_css.html">
 
 <dom-module id="settings-a11y-page">
   <template>
     <style include="settings-shared"></style>
@@ skipping 43 matching lines @@
           <option value="800" i18n-content="delayBeforeClickLong">
           </option>
           <option value="1000" i18n-content="delayBeforeClickVeryLong">
           </option>
         </select>
       </div>
 
       <settings-checkbox pref="{{prefs.settings.a11y.virtual_keyboard}}"
           i18n-values="label:onScreenKeyboardLabel">
       </settings-checkbox>
+      <settings-checkbox pref="{{prefs.settings.a11y.mono_audio}}"
+          i18n-values="label:monoAudioLabel">
+      </settings-checkbox>
       <template is="dom-if" if="[[showExperimentalFeatures_]]">
         <settings-checkbox pref="{{prefs.settings.a11y.caret_highlight}}"
             i18n-values="label:caretHighlightLabel">
         </settings-checkbox>
         <settings-checkbox pref="{{prefs.settings.a11y.cursor_highlight}}"
             i18n-values="label:cursorHighlightLabel">
         </settings-checkbox>
         <settings-checkbox pref="{{prefs.settings.a11y.focus_highlight}}"
             i18n-values="label:focusHighlightLabel">
         </settings-checkbox>
@@ skipping 14 matching lines @@
     <div class="settings-box first">
 </if>
       <div class="button-strip">
         <paper-button i18n-content="moreFeaturesLink" class="primary-button"
             on-tap="onMoreFeaturesTap_"></paper-button>
       </div>
     </div>
   </template>
   <script src="a11y_page.js"></script>
 </dom-module>