[NTP] Tweak app drag and drop.

chrome/browser/resources/ntp/drag_drop_controller.js

Index: chrome/browser/resources/ntp/drag_drop_controller.js
diff --git a/chrome/browser/resources/ntp/drag_drop_controller.js b/chrome/browser/resources/ntp/drag_drop_controller.js
index fe604a41ee9ee583829280cc8e9c4d5209c65a33..2fcf324c91f340d5a1a50e191109a8e35ffd11a9 100644
--- a/chrome/browser/resources/ntp/drag_drop_controller.js
+++ b/chrome/browser/resources/ntp/drag_drop_controller.js
@@ -71,8 +71,10 @@ DragAndDropController.prototype = {
   // starting drag and drop.
   handleMouseDown_: function(e) {
     var item = this.delegate_.getItem(e);
-    if (!item)
+    if (!item) {
+      e.preventDefault();
       return;
+    }
 
     this.startX_ = item.offsetLeft;
     this.startY_ = item.offsetTop;
@@ -96,6 +98,7 @@ DragAndDropController.prototype = {
     // url-list. Instead, we just rely on the dragging of link behavior.
     this.delegate_.dragItem = item;
     item.classList.add('dragging');
+    item.style.zIndex = 2;
 
     e.dataTransfer.effectAllowed = 'copyLinkMove';
   },
@@ -127,9 +130,10 @@ DragAndDropController.prototype = {
 
     this.delegate_.dragItem = null;
     this.delegate_.saveDrag();
+    dragItem.classList.remove('dragging');
 
     setTimeout(function() {
-      dragItem.classList.remove('dragging');
+      dragItem.style.zIndex = 0;
     }, this.delegate_.transitionsDuration + 10);
   },