Update GN build files for new prefs location.

ios/chrome/browser/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.
 
 import("//build/config/features.gni")
 import("//ios/web/js_compile.gni")
 
 declare_args() {
   google_test_gaia_client_id = ""
   google_test_gaia_client_secret = ""
@@ skipping 480 matching lines @@
     "web_resource/web_resource_util.cc",
     "web_resource/web_resource_util.h",
     "xcallback_parameters.h",
     "xcallback_parameters.mm",
   ]
 
   deps = [
     ":about_flags",
     ":injected_js",
     "//base",
-    "//base:prefs",
     "//breakpad:client",
     "//components/about_handler",
     "//components/autofill/core/browser",
     "//components/autofill/core/common",
     "//components/autofill/ios/browser",
     "//components/bookmarks/browser",
     "//components/browser_sync/browser",
     "//components/browser_sync/common",
     "//components/certificate_reporting",
     "//components/component_updater",
@@ skipping 25 matching lines @@
     "//components/metrics_services_manager",
     "//components/net_log",
     "//components/network_time",
     "//components/ntp_snippets",
     "//components/omnibox/browser",
     "//components/open_from_clipboard",
     "//components/password_manager/core/browser",
     "//components/password_manager/sync/browser",
     "//components/policy:policy_component_common",
     "//components/pref_registry",
+    "//components/prefs",
     "//components/profile_metrics",
     "//components/proxy_config",
     "//components/rappor",
     "//components/resources",
     "//components/safe_browsing_db",
     "//components/search",
     "//components/search_engines",
     "//components/security_interstitials/core",
     "//components/security_state",
     "//components/sessions",
@@ skipping 150 matching lines @@
     "//ios/chrome/common",
     "//ios/chrome/test",
     "//ios/public/provider/chrome/browser",
     "//ios/web",
     "//testing/gmock",
     "//testing/gtest",
     "//ui/base",
     "//url",
   ]
 }