Work on "gn check" of content/*

content/public/utility/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.
 
 source_set("utility") {
   sources = [
     "content_utility_client.cc",
     "content_utility_client.h",
     "utility_thread.cc",
     "utility_thread.h",
   ]
 
   configs += [ "//content:content_implementation" ]
 
   deps = [
     "//base",
     "//content:export",
+    "//content/public/common",
     "//content/utility",
     "//ipc",
   ]
+
+  allow_circular_includes_from = [
+    # This target is a pair with content/browser. They always go together and
+    # include headers from each other.
+    "//content/utility",
+  ]
 }