[MD Bookmarks] Refactor focus ring hiding.

chrome/browser/resources/md_bookmarks/item.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/html/icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://bookmarks/actions.html">
-<link rel="import" href="chrome://bookmarks/mouse_focus_behavior.html">
 <link rel="import" href="chrome://bookmarks/shared_style.html">
 <link rel="import" href="chrome://bookmarks/store_client.html">
 
 <dom-module id="bookmarks-item">
   <template>
     <style include="shared-style">
       :host {
         display: block;
         flex-direction: row;
         position: relative;
@@ skipping 48 matching lines @@
       </div>
       <div id="website-title">
         [[item_.title]]
       </div>
       <button is="paper-icon-button-light"
           class="more-vert-button"
           tabindex$="[[ironListTabIndex]]"
           title="$i18n{moreActionsButtonTitle}"
           on-click="onMenuButtonClick_"
           on-dblclick="onMenuButtonDblClick_"
           on-focus="clearMouseFocus">

[tsergeant, 2017/07/12 07:32:00]

This listener doesn't exist anymore.

[calamity, 2017/07/13 08:03:05]

Done.

         <div></div>
         <div></div>
         <div></div>
       </button>
     </div>
   </template>
   <script src="chrome://bookmarks/item.js"></script>
 <dom-module>