Split //ios/chrome/browser/prefs to prevent circular dependencies.

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/buildflag_header.gni")
 import("//build/config/features.gni")
 import("//build/config/ios/rules.gni")
 import("//rlz/features/features.gni")
 import("//third_party/protobuf/proto_library.gni")
 
@@ skipping 157 matching lines @@
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/browser/browser_state:browser_state_impl",
     "//ios/chrome/browser/component_updater",
     "//ios/chrome/browser/first_run",
     "//ios/chrome/browser/history",
     "//ios/chrome/browser/metrics",
     "//ios/chrome/browser/net",
     "//ios/chrome/browser/open_from_clipboard",
     "//ios/chrome/browser/physical_web",
     "//ios/chrome/browser/prefs",
+    "//ios/chrome/browser/prefs:browser_prefs",
     "//ios/chrome/browser/services/gcm",
     "//ios/chrome/browser/translate",
     "//ios/chrome/browser/update_client",
     "//ios/chrome/browser/web_resource",
     "//ios/chrome/common",
     "//ios/public/provider/chrome/browser",
     "//ios/web",
     "//ios/web/public/app",
     "//net",
     "//rlz/features",
@@ skipping 48 matching lines @@
     "//components/proxy_config",
     "//components/ssl_config",
     "//components/variations",
     "//ios/web:test_support",
     "//net",
     "//net:test_support",
     "//testing/gtest",
     "//url",
   ]
 }