[MD Bookmarks] Make drag and drop update data model.

chrome/test/data/webui/md_bookmarks/dnd_manager_test.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.
 
 suite('drag and drop', function() {
   var app;
   var list;
   var sidebar;
   var store;
   var dndManager;
@@ skipping 321 matching lines @@
     dndManager.dragInfo_.handleChromeDragEnter(createDragData(['2']));
     assertEquals(
         DropPosition.NONE,
         dndManager.calculateValidDropPositions_(getListItem('13')));
 
     // Drags onto folders should work as per usual.
     assertEquals(
         DropPosition.ON | DropPosition.ABOVE | DropPosition.BELOW,
         dndManager.calculateValidDropPositions_(getFolderNode('112')));
   });
+
+  test('calculateDropInfo_', function() {
+    // Drops onto the list.

[tsergeant, 2017/03/29 00:32:48]

You could use a helper function here to shorten this, like

function assertDropInfo(parentId, index, element, position){
  assertDeepEquals(...)
}

Seems like it might be helpful if we ever need to refactor this.

[calamity, 2017/03/29 03:35:37]

Done.

+    assertDeepEquals(
+        {
+          parentId: '1',
+          index: 0,
+        },
+        dndManager.calculateDropInfo_({
+          element: getListItem('11'),
+          position: DropPosition.ABOVE,
+        }));
+
+    assertDeepEquals(
+        {
+          parentId: '1',
+          index: 2,
+        },
+        dndManager.calculateDropInfo_({
+          element: getListItem('12'),
+          position: DropPosition.BELOW,
+        }));
+
+    assertDeepEquals(
+        {
+          parentId: '13',
+          index: -1,
+        },
+        dndManager.calculateDropInfo_({
+          element: getListItem('13'),
+          position: DropPosition.ON,
+        }));
+
+    // Drops onto the sidebar.
+    assertDeepEquals(
+        {
+          parentId: '1',
+          index: 4,
+        },
+        dndManager.calculateDropInfo_({
+          element: getFolderNode('15'),
+          position: DropPosition.ABOVE,
+        }));
+
+    assertDeepEquals(
+        {
+          parentId: '1',
+          index: 5,
+        },
+        dndManager.calculateDropInfo_({
+          element: getFolderNode('15'),
+          position: DropPosition.BELOW,
+        }));
+
+    assertDeepEquals(
+        {
+          parentId: '111',
+          index: -1,
+        },
+        dndManager.calculateDropInfo_({
+          element: getFolderNode('111'),
+          position: DropPosition.ON,
+        }));
+  });
+
+  test('simple drag and drop end to end', function() {
+    var dropParentId;
+    var dropIndex;
+    chrome.bookmarkManagerPrivate.drop = function(parentId, index) {
+      dropParentId = parentId;
+      dropIndex = index;
+    };
+
+    var dragElement = getListItem('13');
+    var dragTarget = getListItem('12');
+
+    dispatchDragEvent('dragstart', dragElement);
+    assertDeepEquals(['13'], draggedIds);
+    dndManager.dragInfo_.handleChromeDragEnter(createDragData(draggedIds));
+
+    dispatchDragEvent(
+        'dragover', dragTarget, MockInteractions.topLeftOfNode(dragTarget));
+    assertDragStyle(dragTarget, DRAG_STYLE.ABOVE);
+
+    dispatchDragEvent('drop', dragTarget);
+    assertEquals('1', dropParentId);
+    assertEquals(1, dropIndex);
+
+    dispatchDragEvent('dragend', dragTarget);
+    assertDragStyle(dragTarget, DRAG_STYLE.NONE);
+  });
 });