ntp4: app install improvements

chrome/browser/resources/ntp4/apps_page.js

 // Copyright (c) 2011 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.
 
 cr.define('ntp4', function() {
   'use strict';
 
   var localStrings = new LocalStrings;
 
   var APP_LAUNCH = {
@@ skipping 402 matching lines @@
      */
     appendApp: function(appData, animate) {
       this.appendTile(new App(appData), animate);
     },
 
     /** @inheritdoc */
     doDragOver: function(e) {
       var tile = ntp4.getCurrentlyDraggingTile();
       if (!tile.querySelector('.app')) {
         e.preventDefault();
-        e.dataTransfer.dropEffect = 'copy';
+        this.setDropEffect(e.dataTransfer);
       } else {
         TilePage.prototype.doDragOver.call(this, e);
       }
     },
 
     /** @inheritDoc */
     shouldAcceptDrag: function(e) {
       return ntp4.getCurrentlyDraggingTile() ||
           (e.dataTransfer && e.dataTransfer.types.indexOf('url') != -1);
     },
@@ skipping 76 matching lines @@
 
       var appIds = [];
       for (var i = 0; i < this.tileElements_.length; i++) {
         var tileContents = this.tileElements_[i].firstChild;
         if (tileContents instanceof App)
           appIds.push(tileContents.appId);
       }
 
       chrome.send('reorderApps', [draggedTile.firstChild.appId, appIds]);
     },
+
+    /** @inheritDoc */
+    setDropEffect: function(dataTransfer) {
+      var tile = ntp4.getCurrentlyDraggingTile();
+      if (tile && tile.querySelector('.app'))
+        dataTransfer.dropEffect = 'move';
+      else
+        dataTransfer.dropEffect = 'copy';
+    },
   };
 
   AppsPage.setPromo = function(data) {
     var store = document.querySelector('.webstore');
     if (store)
       store.setAppsPromoData(data);
   };
 
   return {
     APP_LAUNCH: APP_LAUNCH,
     AppsPage: AppsPage,
   };
 });