Make gn check //examples/* pass

examples/recursive_content_handler/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("//mojo/public/mojo_application.gni")
 
 mojo_native_application("recursive_content_handler") {
   sources = [
     "recursive_content_handler.cc"
   ]
 
   deps = [
+    "//base",
     "//mojo/application",
     "//mojo/application:content_handler",
     "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/utility",
     "//mojo/services/public/interfaces/content_handler",
     "//mojo/services/public/interfaces/network",
   ]
 }