[MD Bookmarks] Add keyboard navigation and selection to bookmark list.

chrome/browser/resources/md_bookmarks/reducers.js

Index: chrome/browser/resources/md_bookmarks/reducers.js
diff --git a/chrome/browser/resources/md_bookmarks/reducers.js b/chrome/browser/resources/md_bookmarks/reducers.js
index 0f28d8410509f08b9ed55763c56d86be5f8df5d1..b084724ed07bf7723a61acd6f885d58ca1ae3505 100644
--- a/chrome/browser/resources/md_bookmarks/reducers.js
+++ b/chrome/browser/resources/md_bookmarks/reducers.js
@@ -65,6 +65,17 @@ cr.define('bookmarks', function() {
   };
 
   /**
+   * @param {SelectionState} selectionState
+   * @param {Action} action
+   * @return {SelectionState}
+   */
+  SelectionState.updateAnchor = function(selectionState, action) {
+    return /** @type {SelectionState} */ (Object.assign({}, selectionState, {
+      anchor: action.anchor,
+    }));
+  };
+
+  /**
    * @param {SelectionState} selection
    * @param {Action} action
    * @return {SelectionState}
@@ -81,6 +92,8 @@ cr.define('bookmarks', function() {
       case 'remove-bookmark':
         return SelectionState.deselectDeletedItems(
             selection, action.descendants);
+      case 'update-anchor':
+        return SelectionState.updateAnchor(selection, action);
       default:
         return selection;
     }