[MD Bookmarks] Add draggable sidebar.

chrome/browser/resources/md_bookmarks/list.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_action_menu/cr_action_menu.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
 <link rel="import" href="chrome://resources/cr_elements/shared_style_css.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/shadow.html">
 <link rel="import" href="chrome://bookmarks/item.html">
 <link rel="import" href="chrome://bookmarks/shared_style.html">
 <link rel="import" href="chrome://bookmarks/store_client.html">
 <link rel="import" href="chrome://bookmarks/util.html">
 
 <dom-module id="bookmarks-list">
   <template>
     <style include="shared-style cr-shared-style">
       :host {
-        padding: 20px 32px;
+        overflow-y: auto;
+        padding: 20px 32px 20px calc(32px - var(--splitter-width));
       }
 
       #bookmarksCard {
         @apply(--shadow-elevation-2dp);
         background-color: #fff;
         margin: 0 auto;
         max-width: var(--card-max-width);
-        min-width: var(--card-min-width);
         padding: 8px 0;
       }
 
       .centered-message {
         align-items: center;
         color: #6e6e6e;
         display: flex;
         font-size: 14px;
         font-weight: 500;
         height: 100%;
@@ skipping 41 matching lines @@
         </bookmarks-item>
       </template>
     </div>
     <div class="centered-message"
         hidden$="[[!isEmptyList_(displayedList_.length)]]">
       [[emptyListMessage_(searchTerm_)]]
     </div>
   </template>
   <script src="chrome://bookmarks/list.js"></script>
 </dom-module>