Add more BUILD.gn files to build these targets with GN.

ui/native_theme/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")
+
+component("native_theme") {
+  sources = [
+    "common_theme.cc",
+    "common_theme.h",
+    "fallback_theme.cc",
+    "fallback_theme.h",
+    "native_theme.cc",
+    "native_theme.h",
+    "native_theme_android.cc",
+    "native_theme_android.h",
+    "native_theme_aura.cc",
+    "native_theme_aura.h",
+    "native_theme_base.cc",
+    "native_theme_base.h",
+    "native_theme_mac.h",
+    "native_theme_mac.mm",
+    "native_theme_observer.cc",
+    "native_theme_observer.h",
+    "native_theme_switches.cc",
+    "native_theme_switches.h",
+    "native_theme_win.cc",
+    "native_theme_win.h",
+  ]
+
+  defines = [
+    "NATIVE_THEME_IMPLEMENTATION",
+  ]
+
+  deps = [
+    "//base",
+    "//base/third_party/dynamic_annotations",
+    "//skia",
+    "//ui/base:ui_base",
+    "//ui/gfx",
+    "//ui/gfx/geometry",
+    "//ui/resources",
+  ]
+
+  if (use_aura && is_win) {

[brettw, 2014/05/24 04:49:30]

Heh, I did this file too. You can check it in if you want, but can you grab my
version which handles non-aura builds?
https://codereview.chromium.org/299113002/diff/40001/ui/native_theme/BUILD.gn
Its nice to see our files are otherwise almost identical.

[tfarina, 2014/05/24 05:40:37]

Done.

+    sources += [
+      "native_theme_aurawin.cc",
+      "native_theme_aurawin.h",
+    ]
+  }
+}