[WIP] MD Bookmarks Drag and Drop.

chrome/browser/resources/md_bookmarks/folder_node.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
 <link rel="import" href="chrome://bookmarks/actions.html">
 <link rel="import" href="chrome://bookmarks/icons.html">
 <link rel="import" href="chrome://bookmarks/shared_style.html">
 <link rel="import" href="chrome://bookmarks/store_client.html">
 
 <dom-module id="bookmarks-folder-node">
   <template>
     <style include="shared-style">
       :host {
         --padding-start-per-depth: 36px;
         display: block;
+        position: relative;
       }
 
       .v-centered {
         align-items: center;
         display: flex;
         flex-direction: row;
       }
 
       .menu-label {
         -webkit-margin-start: 16px;
         color: var(--folder-inactive-color);
         font-weight: 500;
         overflow: hidden;
         text-overflow: ellipsis;
         white-space: nowrap;
       }
 
       #container {
         -webkit-padding-start:
             calc(var(--node-depth, 0) * var(--padding-start-per-depth));
         cursor: pointer;
         height: 40px;
       }
 
+      :host(.drag-on) #container {
+        background-color: rgba(66, 133, 244, 0.16);
+      }
+
       #folder-label {
         -webkit-padding-end: 8px;
         color: var(--secondary-text-color);
         flex-grow: 1;
         overflow: hidden;
       }
 
       :host([is-selected-folder_]) .menu-label,
       :host([is-selected-folder_]) #folder-label {
         color: var(--folder-active-color);
@@ skipping 21 matching lines @@
 
       #arrow[is-open] {
         transform: initial;
       }
 
       [no-children] {
         -webkit-padding-start: 52px; /* The width of the arrow and its margin */
       }
     </style>
 
-    <div id="container" class="v-centered" on-tap="selectFolder_">
+    <div id="container" class="v-centered" on-tap="selectFolder_"
+        draggable="[[!isRootFolder_(depth)]]">
       <template is="dom-if" if="[[hasChildFolder_(item_.children)]]">
         <paper-icon-button id="arrow" icon="cr:arrow-drop-down"
             is-open$="[[!isClosed_]]" on-tap="toggleFolder_">
         </paper-icon-button>
       </template>
       <div id="folder-label" class="v-centered">
         <iron-icon icon="[[getFolderIcon_(isSelectedFolder_)]]"
             no-children$="[[!hasChildFolder_(item_.children)]]">
         </iron-icon>
         <div class="menu-label">[[item_.title]]</div>
       </div>
     </div>
     <div id="descendants" hidden$="[[isClosed_]]">
       <template is="dom-repeat"
           items="[[item_.children]]"
           as="child"
           filter="isFolder_">
         <bookmarks-folder-node item-id="[[child]]"
             depth="[[getChildDepth_(depth)]]">
         </bookmarks-folder-node>
       </template>
     </div>
   </template>
   <script src="chrome://bookmarks/folder_node.js"></script>
 </dom-module>