[OnionSoup] Move background_sync.mojom from //content to //third_party/WebKit

content/app/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/features.gni")
 
 content_app_sources = [
   "android/app_jni_registrar.cc",
   "android/app_jni_registrar.h",
@@ skipping 12 matching lines @@
   "mojo/mojo_init.cc",
   "mojo/mojo_init.h",
 ]
 
 content_app_deps = [
   "//base",
   "//base:i18n",
   "//content:export",
   "//content:sandbox_helper_win",
   "//content/public/common:common_sources",
-  "//content/public/common:mojo_bindings",
   "//crypto",
   "//services/shell/public/interfaces",
   "//mojo/edk/system",
+  "//third_party/WebKit/public:mojo_bindings",
   "//ui/base",
   "//ui/gfx",
   "//ui/gfx/geometry",
 ]
 
 if (is_win) {
   content_app_deps += [ "//sandbox" ]
 } else if (is_android) {
   content_app_sources -= [ "content_main.cc" ]
   content_app_deps += [
@@ skipping 62 matching lines @@
   source_set("child") {
     visibility = [ "//content/public/app:child" ]
 
     sources = content_app_sources
     configs += content_app_extra_configs
     deps = content_app_deps
 
     defines = [ "CHROME_MULTIPLE_DLL_CHILD" ]
   }
 }