Add a mojo bridge for PersistentPrefStore.

chrome/browser/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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 1549 matching lines @@
     "//media/midi",
     "//mojo/common",
     "//mojo/edk/system",
     "//mojo/public/cpp/bindings",
     "//mojo/public/js",
     "//net:extras",
     "//ppapi/features",
     "//printing/features",
     "//rlz/features",
     "//services/image_decoder/public/cpp",
+    "//services/preferences/public/cpp",
     "//services/preferences/public/interfaces/",
     "//services/service_manager/public/cpp",
     "//services/shape_detection/public/interfaces",
     "//skia",
     "//sql",
     "//storage/browser",
     "//storage/common",
     "//third_party/WebKit/public:features",
     "//third_party/WebKit/public:image_resources",
     "//third_party/WebKit/public:resources",
@@ skipping 2974 matching lines @@
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }
 
 service_manifest("preferences_manifest") {
   name = "preferences"
   source = "prefs/preferences_manifest.json"
 }