[MD Bookmarks] Allow dragging onto empty bookmark lists.

chrome/test/data/webui/md_bookmarks/dnd_manager_test.js

Index: chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
diff --git a/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js b/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
index 074f5d5beaf24027a9c0b2ca5f41d62a5b944143..25813ac3bc9c06566eacde444db51e9d3d7124cd 100644
--- a/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
+++ b/chrome/test/data/webui/md_bookmarks/dnd_manager_test.js
@@ -338,6 +338,12 @@ suite('drag and drop', function() {
     assertEquals(
         DropPosition.ON | DropPosition.ABOVE | DropPosition.BELOW,
         dndManager.calculateValidDropPositions_(getFolderNode('112')));
+
+    // Drags onto an empty search list do nothing.
+    store.data.search.results = [];
+    store.notifyObservers();
+    assertEquals(
+        DropPosition.NONE, dndManager.calculateValidDropPositions_(list));
   });
 
   test('calculateDropInfo_', function() {
@@ -443,4 +449,35 @@ suite('drag and drop', function() {
     assertEquals(0, autoExpander.lastTimestamp_);
     assertEquals(null, autoExpander.lastElement_);
   });
+
+  test('drag onto empty list', function() {
+    store.data.selectedFolder = '14';
+    store.notifyObservers();
+
+    var dragElement = getFolderNode('15');
+    var dragTarget = list;
+
+    // Dragging onto an empty list.
+    dispatchDragEvent('dragstart', dragElement);
+    dndManager.dragInfo_.handleChromeDragEnter(createDragData(draggedIds));
+
+    dispatchDragEvent('dragover', dragTarget);
+    assertEquals(
+        DropPosition.ON, dndManager.calculateValidDropPositions_(dragTarget));
+    assertDragStyle(dragTarget, DRAG_STYLE.ON);
+
+    dispatchDragEvent('dragend', dragTarget);
+
+    // Dragging onto a non-empty list.
+    store.data.selectedFolder = '11';
+    store.notifyObservers();
+
+    dispatchDragEvent('dragstart', dragElement);
+    dndManager.dragInfo_.handleChromeDragEnter(createDragData(draggedIds));
+
+    dispatchDragEvent('dragover', dragTarget);
+    assertEquals(
+        DropPosition.NONE, dndManager.calculateValidDropPositions_(dragTarget));
+    assertDragStyle(dragTarget, DRAG_STYLE.NONE);
+  });
 });