[MD Bookmarks] Persist collapsed folders between page loads.

chrome/browser/ui/webui/md_bookmarks/md_bookmarks_ui.cc

Index: chrome/browser/ui/webui/md_bookmarks/md_bookmarks_ui.cc
diff --git a/chrome/browser/ui/webui/md_bookmarks/md_bookmarks_ui.cc b/chrome/browser/ui/webui/md_bookmarks/md_bookmarks_ui.cc
index cac3db1bfe3c39ff4e08d05d8b915f42f40a7a0c..bed3e44440ac7c35506d2cb34dd82fdf569a78d3 100644
--- a/chrome/browser/ui/webui/md_bookmarks/md_bookmarks_ui.cc
+++ b/chrome/browser/ui/webui/md_bookmarks/md_bookmarks_ui.cc
@@ -73,6 +73,8 @@ content::WebUIDataSource* CreateMdBookmarksUIHTMLSource(Profile* profile) {
   source->AddResourcePath("api_listener.js", IDR_MD_BOOKMARKS_API_LISTENER_JS);
   source->AddResourcePath("app.html", IDR_MD_BOOKMARKS_APP_HTML);
   source->AddResourcePath("app.js", IDR_MD_BOOKMARKS_APP_JS);
+  source->AddResourcePath("constants.html", IDR_MD_BOOKMARKS_CONSTANTS_HTML);
+  source->AddResourcePath("constants.js", IDR_MD_BOOKMARKS_CONSTANTS_JS);
   source->AddResourcePath("dnd_manager.html",
                           IDR_MD_BOOKMARKS_DND_MANAGER_HTML);
   source->AddResourcePath("dnd_manager.js", IDR_MD_BOOKMARKS_DND_MANAGER_JS);