[Password Manager] Switch password manager code to use "base/feature_list.h".

components/password_manager/core/common/BUILD.gn

 # Copyright 2014 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.
 
 source_set("common") {
   sources = [
     "credential_manager_types.cc",
     "credential_manager_types.h",
     "experiments.cc",
     "experiments.h",
+    "password_manager_features.cc",
+    "password_manager_features.h",
     "password_manager_pref_names.cc",
     "password_manager_pref_names.h",
     "password_manager_switches.cc",
     "password_manager_switches.h",
     "password_manager_ui.h",
   ]
 
   deps = [
     "//base",
     "//components/autofill/core/common",
     "//sql",
     "//url",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "credential_manager_types_unittest.cc",
   ]
   deps = [
     ":common",
     "//base",
     "//components/autofill/core/common",
     "//sql",
     "//testing/gtest",
     "//url",
   ]
 }