Update GN build files for new prefs location.

components/user_manager/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.
 
 component("user_manager") {
   sources = [
     "empty_user_info.cc",
     "empty_user_info.h",
     "user_info.cc",
     "user_info.h",
@@ skipping 20 matching lines @@
       "user.h",
       "user_image/user_image.cc",
       "user_image/user_image.h",
       "user_manager.cc",
       "user_manager.h",
       "user_manager_base.cc",
       "user_manager_base.h",
       "user_type.h",
     ]
     deps += [
-      "//base:prefs",
+      "//components/prefs",
       "//components/session_manager/core",
       "//google_apis",
       "//url",
     ]
   }
 }
 
 source_set("test_support") {
   testonly = true
   if (is_chromeos) {
     sources = [
       "fake_user_manager.cc",
       "fake_user_manager.h",
     ]
     deps = [
       ":user_manager",
       "//base",
       "//chromeos:chromeos",
       "//components/signin/core/account_id",
       "//skia",
       "//ui/base",
     ]
   }
 }