[MD Bookmarks] Add skeleton for MD Bookmarks.

chrome/browser/resources/md_bookmarks/app.js

Index: chrome/browser/resources/md_bookmarks/app.js
diff --git a/chrome/browser/resources/md_bookmarks/app.js b/chrome/browser/resources/md_bookmarks/app.js
new file mode 100644
index 0000000000000000000000000000000000000000..0d79074a5202a434071f6d0b429f198882e86a21
--- /dev/null
+++ b/chrome/browser/resources/md_bookmarks/app.js
@@ -0,0 +1,23 @@
+// Copyright 2016 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.
+
+Polymer({
+  is: 'bookmarks-app',
+
+  properties: {
+    selectedId: String,
+
+    /** @type {BookmarkTreeNode} */
+    selectedNode: Object,
+
+    /** @type {BookmarkTreeNode} */
+    rootNode: Object,
+  },
+
+  /** @override */
+  attached: function() {
+    /** @type {BookmarksStoreElement} */ (this.$$('bookmarks-store'))
+        .initializeStore();
+  },
+});