MD Bookmarks: Disable 'Open in Incognito Window' when Incognito is disabled

chrome/browser/resources/md_bookmarks/reducers.js

 // Copyright 2017 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.
 
 /**
  * @fileoverview Module of functions which produce a new page state in response
  * to an action. Reducers (in the same sense as Array.prototype.reduce) must be
  * pure functions: they must not modify existing state objects, or make any API
  * calls.
  */
@@ skipping 377 matching lines @@
     var closed = !action.open;
     var newClosedFolders = new Set(closedFolders);
     if (closed)
       newClosedFolders.add(action.id);
     else
       newClosedFolders.delete(action.id);
 
     return newClosedFolders;
   };
 
+  var PreferencesState = {};
+
+  /**
+   * @param {PreferencesState} prefs
+   * @param {Action} action
+   * @return {PreferencesState}
+   */
+  PreferencesState.updatePrefs = function(prefs, action) {
+    switch (action.name) {
+      case 'set-incognito-availability':
+        return /** @type {PreferencesState} */ (Object.assign({}, prefs, {
+          incognitoAvailability: action.value,
+        }));
+      default:
+        return prefs;
+    }
+  };
+
   /**
    * @param {ClosedFolderState} closedFolders
    * @param {Action} action
    * @param {NodeMap} nodes
    * @return {ClosedFolderState}
    */
   ClosedFolderState.updateClosedFolders = function(
       closedFolders, action, nodes) {
     switch (action.name) {
       case 'change-folder-open':
@@ skipping 22 matching lines @@
    * @param {Action} action
    * @return {!BookmarksPageState}
    */
   function reduceAction(state, action) {
     return {
       nodes: NodeState.updateNodes(state.nodes, action),
       selectedFolder: SelectedFolderState.updateSelectedFolder(
           state.selectedFolder, action, state.nodes),
       closedFolders: ClosedFolderState.updateClosedFolders(
           state.closedFolders, action, state.nodes),
+      prefs: PreferencesState.updatePrefs(state.prefs, action),
       search: SearchState.updateSearch(state.search, action),
       selection: SelectionState.updateSelection(state.selection, action),
     };
   }
 
   return {
     reduceAction: reduceAction,
     ClosedFolderState: ClosedFolderState,
     NodeState: NodeState,
+    PreferencesState: PreferencesState,
     SearchState: SearchState,
     SelectedFolderState: SelectedFolderState,
     SelectionState: SelectionState,
   };
 });