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 72 matching lines @@
         <div class="start">
           <div id="displayMirrorCheckboxLabel">$i18n{displayMirror}</div>
           <div class="secondary">[[getDisplayMirrorText_(displays)]]</div>
         </div>
         <paper-toggle-button checked="[[isMirrored_(displays)]]"
             on-tap="onMirroredTap_"
             aria-labelledby="displayMirrorCheckboxLabel">
       </div>
       <div class="settings-box embedded"
           hidden$="[[!showDisplaySelectMenu_(displays, selectedDisplay)]]">
-        <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">$i18n{displayScreenExtended}</option>
           </select>
           <span class="md-select-underline"></span>
         </div>
       </div>
       <div class="settings-box embedded two-line">
         <div class="start textarea layout vertical">
           <div>$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>
       <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>
       <div class="settings-box embedded two-line"
@@ skipping 25 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>