[Extensions] Remove FeatureSwitch::easy_off_store_install

chrome/browser/resources/md_extensions/drop_overlay.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function() {
   'use strict';
 
   Polymer({
     is: 'extensions-drop-overlay',
     created: function() {
       this.hidden = true;
-      if (loadTimeData.getBoolean('offStoreInstallEnabled'))
-        return;
       var dragTarget = document.documentElement;
       this.dragWrapperHandler_ =
           new extensions.DragAndDropHandler(true, dragTarget);
       dragTarget.addEventListener('extension-drag-started', function() {
         this.hidden = false;
       }.bind(this));
       dragTarget.addEventListener('extension-drag-ended', function() {
         this.hidden = true;
       }.bind(this));
       this.dragWrapper_ =
           new cr.ui.DragWrapper(dragTarget, this.dragWrapperHandler_);
     },
   });
 })();