Improve GN header checker, make //ui pass.

ui/base/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/ui.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 }
@@ skipping 240 matching lines @@
     "win/scoped_ole_initializer.h",
     "win/shell.cc",
     "win/shell.h",
     "win/touch_input.cc",
     "win/touch_input.h",
     "win/window_event_target.cc",
     "win/window_event_target.h",
     "window_open_disposition.cc",
     "window_open_disposition.h",
     "work_area_watcher_observer.h",
-    "x/x11_foreign_window_manager.cc",
-    "x/x11_foreign_window_manager.h",
-    "x/x11_menu_list.cc",
-    "x/x11_menu_list.h",
-    "x/x11_util.cc",
-    "x/x11_util.h",
-    "x/x11_util_internal.h",
   ]
 
   if (is_win) {
     sources += [ "touch/touch_device_win.cc" ]
   } else if (is_android) {
     sources += [ "touch/touch_device_android.cc" ]
   } else if (use_ozone) {
     sources += [ "touch/touch_device_ozone.cc" ]
   } else if (use_aura && use_x11) { 
     sources += [ "touch/touch_device_aurax11.cc" ]
   } else {
     # Empty implementation for all other cases.
     sources += [ "touch/touch_device.cc" ]
   }
 
   defines = [ "UI_BASE_IMPLEMENTATION" ]
 
+  public_deps = [
+    "//base",
+    "//skia",
+    "//ui/events/platform",
+    "//ui/events:events_base",
+    "//ui/gfx",
+    "//ui/gfx/geometry",
+  ]
   deps = [
-    "//base",
     "//base/third_party/dynamic_annotations",
     "//base:base_static",
     "//base:i18n",
     "//net",
-    "//skia",
     "//third_party/icu",
-    "//ui/events/platform",
-    "//ui/events:events_base",
-    "//ui/gfx",
-    "//ui/gfx/geometry",
     "//ui/resources",
     "//ui/strings",
     "//url",
   ]
-  # We expose these things in our headers:
-  forward_dependent_configs_from = [
-    "//ui/gfx",
-  ]
 
   if (build_ime) {
     if (!is_android) {
       deps += [
         "//ui/events",
       ]
     }
 
     sources += [
       "ime/candidate_window.cc",
@@ skipping 121 matching lines @@
     deps += [
       "//ui/events",
     ]
   } else {
     sources -= [
       "cursor/cursor.cc",
       "cursor/cursor.h",
       "dragdrop/drag_utils_aura.cc",
     ]
   }
-  if (!use_x11) {
-    sources -= [
+  if (use_x11) {
+    sources += [
       "x/x11_foreign_window_manager.cc",
       "x/x11_foreign_window_manager.h",
       "x/x11_menu_list.cc",
       "x/x11_menu_list.h",
       "x/x11_util.cc",
       "x/x11_util.h",
       "x/x11_util_internal.h",
     ]
+    deps += [ "//ui/gfx/x" ]
   }
 
   if (!use_aura || !is_linux) {
     sources -= [
       "resource/resource_bundle_auralinux.cc",
     ]
   }
 
   if (use_aura && is_win) {
     sources -= [
@@ skipping 190 matching lines @@
   testonly = true
   sources = [
     "test/ui_controls.h",
     "test/ui_controls_aura.cc",
     "test/ui_controls_internal_win.cc",
     "test/ui_controls_internal_win.h",
     "test/ui_controls_mac.mm",
     "test/ui_controls_win.cc",
   ]
 
+  public_deps = [
+    ":base",
+  ]
   deps = [
-    ":base",
     "//base",
     "//skia",
     "//testing/gtest",
     "//ui/events:events_base",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
 
   if (build_ime) {
     sources += [
@@ skipping 215 matching lines @@
     deps += [
       "//ui/aura:test_support",
       "//ui/events:gesture_detection",
       #'../chromeos/chromeos.gyp:chromeos',  TODO(GYP)
       #'chromeos/ui_chromeos.gyp:ui_chromeos',
     ]
   }
 }
 }
 # TODO(GYP) Mac (ui_unittest_bundle) and Android (ui_unittests_apk).