Move undo files into //components/undo

components/undo/BUILD.gn

+# Copyright 2015 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.
+
+static_library("undo") {
+  sources = [
+    "bookmark_renumber_observer.h",
+    "bookmark_undo_service.cc",
+    "bookmark_undo_service.h",
+    "bookmark_undo_utils.cc",
+    "bookmark_undo_utils.h",
+    "undo_manager.cc",
+    "undo_manager.h",
+    "undo_manager_observer.h",
+    "undo_operation.h",
+  ]
+
+  deps = [
+    "//base",
+    "//components/bookmarks/browser",
+    "//components/keyed_service/core",
+    "//components/strings",
+    "//ui/base",
+  ]
+}
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "bookmark_undo_service_test.cc",
+    "undo_manager_test.cc",
+  ]
+
+  deps = [
+    "//components/bookmarks/test",
+    "//components/undo",
+    "//testing/gtest",
+  ]
+}