add aria-labelledby to options device sliders

chrome/browser/resources/options/browser_options.html

 <div id="settings" class="page" hidden>
   <header>
     <h1 i18n-content="settingsTitle"></h1>
   </header>
   <include src="automatic_settings_reset_banner.html">
 <if expr="chromeos">
   <link rel="import" href="chrome://resources/cr_elements/network/cr_network_icon.html">
   <link rel="import" href="chrome://resources/cr_elements/network/cr_onc_types.html">
   <include src="secondary_user_banner.html">
   <section id="network-section-cros">
@@ skipping 89 matching lines @@
         <span i18n-content="showWindowDecorations"></span>
     </label></div>
 </if>
   </section>
 <if expr="chromeos">
   <section id="device-section">
     <h3 i18n-content="sectionTitleDevice"></h3>
     <div>
       <span i18n-content="deviceGroupDescription"></span>
       <div id="touchpad-settings" class="settings-row" hidden>
-        <span class="option-name" i18n-content="touchpadSpeed"></span>
+        <span id="touchpad-speed-label" class="option-name"
+            i18n-content="touchpadSpeed"></span>
         <input id="touchpad-sensitivity-range" type="range" min="1" max="5"
-            pref="settings.touchpad.sensitivity2" class="touch-slider">
+            pref="settings.touchpad.sensitivity2" class="touch-slider"
+            aria-labelledby="touchpad-speed-label">
       </div>
       <div id="mouse-settings" class="settings-row" hidden>
-        <span class="option-name" i18n-content="mouseSpeed"></span>
+        <span id="mouse-speed-label" class="option-name"
+            i18n-content="mouseSpeed"></span>
         <input id="mouse-sensitivity-range" type="range" min="1" max="5"
-            pref="settings.mouse.sensitivity2" class="touch-slider">
+            pref="settings.mouse.sensitivity2" class="touch-slider"
+            aria-labelledby="mouse-speed-label">
       </div>
       <div id="no-pointing-devices" i18n-content="noPointingDevices"
           class="settings-row" hidden>
       </div>
       <div class="settings-row">
         <button id="pointer-settings-button" hidden>
         </button>
         <button id="keyboard-settings-button"
             i18n-content="keyboardSettingsButtonTitle">
         </button>
@@ skipping 992 matching lines @@
       </button>
     </div>
   </section>
   </div>  <!-- advanced-settings-container -->
   </div>  <!-- advanced-settings -->
   <footer id="advanced-settings-footer">
     <a is="action-link" id="advanced-settings-expander"
         i18n-content="showAdvancedSettings"></a>
   </footer>
 </div>