Improve GN header checker, make //ui pass.

ui/base/BUILD.gn

Index: ui/base/BUILD.gn
diff --git a/ui/base/BUILD.gn b/ui/base/BUILD.gn
index 2ac985fa1b97d4dfc9c062d5134527ead7fde3f4..0436bec3a2df2aac38e5aee21380289a7d9c9b13 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -261,13 +261,6 @@ component("base") {
     "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) {
@@ -285,26 +278,24 @@ component("base") {
 
   defines = [ "UI_BASE_IMPLEMENTATION" ]
 
-  deps = [
+  public_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",
+  ]
+  deps = [
+    "//base/third_party/dynamic_annotations",
+    "//base:base_static",
+    "//base:i18n",
+    "//net",
+    "//third_party/icu",
     "//ui/resources",
     "//ui/strings",
     "//url",
   ]
-  # We expose these things in our headers:
-  forward_dependent_configs_from = [
-    "//ui/gfx",
-  ]
 
   if (build_ime) {
     if (!is_android) {
@@ -446,8 +437,8 @@ component("base") {
       "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",
@@ -456,6 +447,7 @@ component("base") {
       "x/x11_util.h",
       "x/x11_util_internal.h",
     ]
+    deps += [ "//ui/gfx/x" ]
   }
 
   if (!use_aura || !is_linux) {
@@ -666,8 +658,10 @@ source_set("test_support") {
     "test/ui_controls_win.cc",
   ]
 
-  deps = [
+  public_deps = [
     ":base",
+  ]
+  deps = [
     "//base",
     "//skia",
     "//testing/gtest",