[MD settings] show icon when slider controlled by something

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

 <link rel="import" href="chrome://resources/cr_elements/cr_slider/cr_slider.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-radio-button/paper-radio-button.html">
 <link rel="import" href="../controls/settings_radio_group.html">
 <link rel="import" href="../controls/settings_toggle_button.html">
 <link rel="import" href="device_page_browser_proxy.html">
 <link rel="import" href="../settings_shared_css.html">
 
 <dom-module id="settings-pointers">
   <template>
@@ skipping 18 matching lines @@
       <!-- Subsection title only appears if both mouse and touchpad exist. -->
       <h2 hidden$="[[!hasTouchpad]]">$i18n{mouseTitle}</h2>
       <div class="settings-box first">
         <settings-toggle-button class="start"
             pref="{{prefs.settings.mouse.primary_right}}"
             label="$i18n{mouseSwapButtons}">
         </settings-toggle-button>
       </div>
       <div class="settings-box">
         <div class="start" id="mouseSpeedLabel">$i18n{mouseSpeed}</div>
-        <cr-slider value="{{prefs.settings.mouse.sensitivity2.value}}"
+        <cr-slider pref="{{prefs.settings.mouse.sensitivity2}}"
             tick-values="[[sensitivityValues_]]"
             aria-labelledby="mouseSpeedLabel"
             label-min="$i18n{pointerSlow}"
             label-max="$i18n{pointerFast}">
         </cr-slider>
       </div>
     </div>
     <div id="touchpad" hidden$="[[!hasTouchpad]]"
         class$="[[getSubsectionClass_(hasMouse, hasTouchpad)]]">
       <!-- Subsection title only appears if both mouse and touchpad exist. -->
@@ skipping 31 matching lines @@
                 on-keydown="onLearnMoreLinkActivated_">
               $i18n{naturalScrollLearnMore}
             </a>
           </paper-radio-button>
         </settings-radio-group>
       </div>
     </div>
   </template>
   <script src="pointers.js"></script>
 </dom-module>