ntp4: fix one more small dragging glitch.

chrome/browser/resources/ntp4/tile_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';
 
   /**
    * Creates a new Tileobject. Tiles wrap content on a TilePage, providing
    * some styling and drag functionality.
@@ skipping 429 matching lines @@
       tile.setGridPosition(animatedX, animatedY);
       tile.firstChild.setBounds(layout.tileWidth,
                                 realX - animatedX,
                                 realY - animatedY);
 
       // This code calculates whether the tile needs to show a clone of itself
       // wrapped around the other side of the tile grid.
       var offTheRight = col == layout.numRowTiles ||
           (col == layout.numRowTiles - 1 && tile.hasDoppleganger());
       var offTheLeft = col == -1 || (col == 0 && tile.hasDoppleganger());
-      if (this.dragEnters_ > 0 && (offTheRight || offTheLeft)) {
+      if (this.isCurrentDragTarget_ && (offTheRight || offTheLeft)) {
         var sign = offTheRight ? 1 : -1;
         tile.showDoppleganger(-layout.numRowTiles * layout.colWidth * sign,
                               layout.rowHeight * sign);
       } else {
         tile.clearDoppleganger();
       }
     },
 
     /**
      * Gets the index of the tile that should occupy coordinate (x, y). Note
@@ skipping 38 matching lines @@
       }
     },
 
     /**
      * The tile grid has an image mask which fades at the edges. We only show
      * the mask when there is an active drag; it obscures doppleganger tiles
      * as they enter or exit the grid.
      * @private
      */
     updateMask_: function() {
-      if (this.dragEnters_ == 0) {
+      if (!this.isCurrentDragTarget_) {
         this.style.WebkitMaskBoxImage = '';
         return;
       }
 
       var leftMargin = this.layoutValues_.leftMargin;
       var fadeDistance = 20;
       var gradient =
           '-webkit-linear-gradient(left,' +
               'transparent, ' +
               'transparent ' + (leftMargin - fadeDistance) + 'px, ' +
@@ skipping 164 matching lines @@
     /**
      * Performs all actions necessary when the user completes a drop.
      * @param {Event} e A mouseover event for the drag drop.
      * @private
      */
     doDrop_: function(e) {
       e.stopPropagation();
       this.isCurrentDragTarget_ = false;
 
       var index = this.currentDropIndex_;
-      if ((index == this.dragItemIndex_) && this.withinPageDrag_)
-        return;
-
-      var adjustedIndex = this.currentDropIndex_ +
-          (index > this.dragItemIndex_ ? 1 : 0);
-      if (TilePage.currentlyDraggingTile) {
-        this.tileGrid_.insertBefore(
-            TilePage.currentlyDraggingTile,
-            this.tileElements_[adjustedIndex]);
-      } else {
-        this.addOutsideData(e.dataTransfer, adjustedIndex);
+      // Only change data if this was not a 'null drag'.
+      if (!((index == this.dragItemIndex_) && this.withinPageDrag_)) {
+        var adjustedIndex = this.currentDropIndex_ +
+            (index > this.dragItemIndex_ ? 1 : 0);
+        if (TilePage.currentlyDraggingTile) {
+          this.tileGrid_.insertBefore(
+              TilePage.currentlyDraggingTile,
+              this.tileElements_[adjustedIndex]);
+        } else {
+          this.addOutsideData(e.dataTransfer, adjustedIndex);
+        }
       }
 
       this.classList.remove('animating-tile-page');
       this.cleanUpDrag_();
     },
 
     /**
      * Makes sure all the tiles are in the right place after a drag is over.
      * @private
      */
@@ skipping 107 matching lines @@
       // This should not get called unless there is a non-default
       // implementation.
       assert(false);
     },
   };
 
   return {
     TilePage: TilePage,
   };
 });