MD Settings: convert paper-icon-button to paper-icon-button-light.

chrome/browser/resources/settings/site_settings/zoom_levels.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-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/html/web_ui_listener_behavior.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="site_settings_behavior.html">
 <link rel="import" href="site_settings_prefs_browser_proxy.html">
 
 <dom-module id="zoom-levels">
   <template>
     <style include="settings-shared">
       :host {
@@ skipping 13 matching lines @@
       <template is="dom-repeat" items="[[sites_]]" id="list">
         <div class="list-item">
           <div class="favicon-image"
               style$="[[computeSiteIcon(item.originForFavicon)]]">
           </div>
           <div class="middle">
             <div>[[item.displayName]]</div>
           </div>
           <div class="zoom-label">[[item.zoom]]</div>
           <div>
-            <paper-icon-button icon="cr:clear" on-tap="removeZoomLevel_"
-                title="$i18n{siteSettingsRemoveZoomLevel}"></paper-icon-button>
+            <button is="paper-icon-button-light" class="icon-clear"
+                on-tap="removeZoomLevel_"
+                title="$i18n{siteSettingsRemoveZoomLevel}"></button>
           </div>
         </div>
       </template>
       <template is="dom-if" if="[[!sites_.length]]">
         <div id="empty">
           $i18n{siteSettingsNoZoomedSites}
         </div>
       </template>
     </div>
   </template>
   <script src="zoom_levels.js"></script>
 </dom-module>