[MD Bookmarks] Fix drag and drop on Mac.

chrome/browser/resources/md_bookmarks/dnd_manager.js

 // Copyright 2017 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('bookmarks', function() {
   /**
    * @param {BookmarkElement} element
    * @return {boolean}
    */
   function isBookmarkItem(element) {
@@ skipping 187 matching lines @@
     /**
      * The style that was applied to indicate the drop location.
      * @private {?string|null}
      */
     this.lastIndicatorClassName_ = null;
 
     /**
      * Used to instantly remove the indicator style in tests.
      * @private {function((Function|null|string), number)}
      */
-    this.setTimeout_ = window.setTimeout.bind(window);
+    this.setTimeout = window.setTimeout.bind(window);
   }
 
   DropIndicator.prototype = {
     /**
      * Applies the drop indicator style on the target element and stores that
      * information to easily remove the style in the future.
      * @param {HTMLElement} indicatorElement
      * @param {DropPosition} position
      */
     addDropIndicatorStyle: function(indicatorElement, position) {
@@ skipping 34 matching lines @@
       this.addDropIndicatorStyle(indicatorElement, position);
     },
 
     /**
      * Stop displaying the drop indicator.
      */
     finish: function() {
       // The use of a timeout is in order to reduce flickering as we move
       // between valid drop targets.
       window.clearTimeout(this.removeDropIndicatorTimer_);
-      this.removeDropIndicatorTimer_ = this.setTimeout_(function() {
+      this.removeDropIndicatorTimer_ = this.setTimeout(function() {
         this.removeDropIndicatorStyle();
       }.bind(this), 100);
     },
-
-    disableTimeoutForTesting: function() {
-      this.setTimeout_ = function(fn, timeout) {
-        fn();
-      };
-    },
   };
 
   /**
    * Manages drag and drop events for the bookmarks-app.
    * @constructor
    */
   function DNDManager() {
     /** @private {bookmarks.DragInfo} */
     this.dragInfo_ = null;
 
     /** @private {?DropDestination} */
     this.dropDestination_ = null;
 
     /** @private {bookmarks.DropIndicator} */
     this.dropIndicator_ = null;
 
     /** @private {Object<string, function(!Event)>} */
     this.documentListeners_ = null;
+
+    /**
+     * Used to instantly clearDragData in tests.
+     * @private {function((Function|null|string), number)}
+     */
+    this.setTimeout = window.setTimeout.bind(window);
   }
 
   DNDManager.prototype = {
     init: function() {
       this.dragInfo_ = new DragInfo();
       this.dropIndicator_ = new DropIndicator();
       this.autoExpander_ = new AutoExpander();
 
       this.documentListeners_ = {
         'dragstart': this.onDragStart_.bind(this),
@@ skipping 76 matching lines @@
       }
 
       return {
         index: index,
         parentId: parentId,
       };
     },
 
     /** @private */
     clearDragData_: function() {
-      this.dragInfo_.clearDragData();
-      this.dropDestination_ = null;
-      this.dropIndicator_.finish();
+      // Defer the clearing of the data so that the bookmark manager API's drop
+      // event doesn't clear the drop data before the web drop event has a
+      // chance to execute (on Mac).
+      this.setTimeout_(function() {
+        this.dragInfo_.clearDragData();
+        this.dropDestination_ = null;
+        this.dropIndicator_.finish();
+      }.bind(this), 0);
     },
 
     /**
      * @private
      * @param {Event} e
      */
     onDragStart_: function(e) {
       var dragElement = getBookmarkElement(e.path);
       if (!dragElement)
         return;
@@ skipping 207 matching lines @@
         return state.selectedFolder &&
             state.nodes[state.selectedFolder].children.length == 0;
       }
 
       // We can only drop on a folder.
       if (getBookmarkNode(overElement).url)
         return false;
 
       return !this.dragInfo_.isDraggingChildBookmark(overElement.itemId)
     },
+
+    disableTimeoutsForTesting: function() {
+      this.setTimeout_ = function(fn) {
+        fn();
+      };
+      this.dropIndicator_.setTimeout = this.setTimeout_;
+    }
   };
 
   return {
     DNDManager: DNDManager,
     DragInfo: DragInfo,
     DropIndicator: DropIndicator,
   };
 });