MD-Settings: A11y - Label drop down menus.

chrome/browser/resources/settings/device_page/display.html

 <link rel="import" href="chrome://resources/html/polymer.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/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.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="chrome://resources/polymer/v1_0/paper-tabs/paper-tabs.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-toggle-button/paper-toggle-button.html">
 <link rel="import" href="display_layout.html">
 <link rel="import" href="display_overscan_dialog.html">
@@ skipping 100 matching lines @@
           <paper-toggle-button checked="[[unifiedDesktopMode_]]"
               on-tap="onUnifiedDesktopTap_"
               aria-labelledby="displayUnifiedDesktopCheckboxLabel">
           </paper-toggle-button>
         </div>
       </template>
 
       <template is="dom-if" restamp
           if="[[showDisplaySelectMenu_(displays, selectedDisplay)]]">
         <div class="settings-box embedded">
-          <div class="start">$i18n{displayScreenTitle}</div>
+          <div id="displayScreenTitle" class="start">
+            $i18n{displayScreenTitle}
+          </div>
           <div class="md-select-wrapper">
             <select class="md-select" on-change="updatePrimaryDisplay_"
+                aria-labelledby="displayScreenTitle"
                 value="[[getDisplaySelectMenuIndex_(
                     selectedDisplay, primaryDisplayId)]]">
               <option value="0">$i18n{displayScreenPrimary}</option>
               <option value="1">$i18n{displayScreenExtended}</option>
             </select>
             <span class="md-select-underline"></span>
           </div>
         </div>
       </template>
 
       <div class="settings-box embedded two-line">
         <div class="start textarea layout vertical">
           <div>$i18n{displayResolutionTitle}</div>
           <div class="secondary layout self-start">
             [[getResolutionText_(selectedDisplay, selectedModePref_.value)]]
           </div>
         </div>
         <settings-slider disabled="[[!enableSetResolution_(selectedDisplay)]]"
             tick-values="[[modeValues_]]" pref="{{selectedModePref_}}"
             on-change="onSelectedModeChange_">
         </settings-slider>
       </div>
 
       <template is="dom-if" if="[[!unifiedDesktopMode_]]" restamp>
         <div class="settings-box embedded">
-          <div class="start textarea">$i18n{displayOrientation}</div>
+          <div id="displayOrientation" class="start textarea">
+            $i18n{displayOrientation}
+          </div>
           <div class="md-select-wrapper">
             <select class="md-select" value="[[selectedDisplay.rotation]]"
+                aria-labelledby="displayOrientation"
                 on-change="onOrientationChange_">
               <option value="0">$i18n{displayOrientationStandard}</option>
               <option value="90">90</option>
               <option value="180">180</option>
               <option value="270">270</option>
             </select>
             <span class="md-select-underline"></span>
           </div>
         </div>
       </template>
@@ skipping 27 matching lines @@
           </div>
         </div>
         <button class="subpage-arrow" is="paper-icon-button-light"
             aria-label="$i18n{displayTouchCalibrationTitle}"
             aria-describedby="touchCalibrationSecondary"></button>
       </div>
     </div>
   </template>
   <script src="display.js"></script>
 </dom-module>