Improve GN header checker, make //ui pass.

ui/accessibility/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("//extensions/generated_extensions_api.gni")
 
 component("accessibility") {
   sources = [
     "ax_node.cc",
     "ax_node.h",
@@ skipping 16 matching lines @@
     "platform/ax_platform_node.h",
     "platform/ax_platform_node_base.cc",
     "platform/ax_platform_node_base.h",
     "platform/ax_platform_node_delegate.h",
     "platform/ax_platform_node_mac.h",
     "platform/ax_platform_node_mac.mm",
   ]
 
   defines = [ "ACCESSIBILITY_IMPLEMENTATION" ]
 
-  forward_dependent_configs_from = [ ":ax_gen" ]
-
-  deps = [
+  public_deps = [
     ":ax_gen",
     "//base",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
 }
 
 source_set("test_support") {
   sources = [
     "tree_generator.cc",
@@ skipping 22 matching lines @@
     "//ui/gfx/geometry",
   ]
 }
 
 generated_extensions_api("ax_gen") {
   sources = [ "ax_enums.idl" ]
   deps = [ "//base/third_party/dynamic_annotations" ]
   root_namespace = "ui"
   schemas = true
 }