Update GN build files for new prefs location.

mash/wallpaper/BUILD.gn

 # Copyright 2016 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.
 
 import("//build/config/ui.gni")
 import("//mojo/public/mojo_application.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 
 mojo_native_application("wallpaper") {
   sources = [
     "wallpaper.cc",
   ]
 
   deps = [
     "//base",
-    "//base:prefs",
     "//components/filesystem/public/cpp/prefs",
     "//components/filesystem/public/interfaces",
     "//components/mus/public/cpp",
     "//components/mus/public/interfaces",
+    "//components/prefs",
     "//mash/wm/public/interfaces",
     "//mojo/public/cpp/bindings",
     "//mojo/services/tracing/public/cpp",
     "//mojo/shell/public/cpp",
     "//mojo/shell/public/cpp:sources",
     "//mojo/shell/public/interfaces",
     "//ui/views",
     "//ui/views/mus:for_mojo_application",
     "//url",
   ]
 
   resources = [ "$root_out_dir/views_mus_resources.pak" ]
 
   data_deps = [
     "//components/mus",
   ]
 }