[MD Bookmarks] Add undo/redo functionality to MD Bookmarks.

chrome/browser/bookmarks/bookmark_model_factory.cc

Index: chrome/browser/bookmarks/bookmark_model_factory.cc
diff --git a/chrome/browser/bookmarks/bookmark_model_factory.cc b/chrome/browser/bookmarks/bookmark_model_factory.cc
index 46069a63f171a5c6647cf839d8682b6dfe99ae56..e6d62d6a97b6c60de8dc7999b2f2e44fec14b28f 100644
--- a/chrome/browser/bookmarks/bookmark_model_factory.cc
+++ b/chrome/browser/bookmarks/bookmark_model_factory.cc
@@ -15,6 +15,7 @@
 #include "chrome/browser/bookmarks/startup_task_runner_service_factory.h"
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/webui/md_bookmarks/md_bookmarks_ui.h"
 #include "chrome/browser/undo/bookmark_undo_service_factory.h"
 #include "chrome/common/chrome_switches.h"
 #include "components/bookmarks/browser/bookmark_model.h"
@@ -27,6 +28,21 @@
 
 using bookmarks::BookmarkModel;
 
+namespace {
+
+bool IsBookmarkUndoServiceEnabled() {
+  bool register_bookmark_undo_service_as_observer = true;
+#if !defined(OS_ANDROID)
+  register_bookmark_undo_service_as_observer =
+      base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBookmarkUndo) ||
+      MdBookmarksUI::IsEnabled();
+#endif  // !defined(OS_ANDROID)
+  return register_bookmark_undo_service_as_observer;
+}
+
+}  // namespace
+
 // static
 BookmarkModel* BookmarkModelFactory::GetForBrowserContext(
     content::BrowserContext* context) {
@@ -69,13 +85,7 @@ KeyedService* BookmarkModelFactory::BuildServiceInstanceFor(
                            ->GetBookmarkTaskRunner(),
                        content::BrowserThread::GetTaskRunnerForThread(
                            content::BrowserThread::UI));
-  bool register_bookmark_undo_service_as_observer = true;
-#if !defined(OS_ANDROID)
-  register_bookmark_undo_service_as_observer =
-      base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableBookmarkUndo);
-#endif  // !defined(OS_ANDROID)
-  if (register_bookmark_undo_service_as_observer)
+  if (IsBookmarkUndoServiceEnabled())
     BookmarkUndoServiceFactory::GetForProfile(profile)->Start(bookmark_model);
 
   return bookmark_model;