Add GN build for Linux sandbox.

ui/gfx/x/BUILD.gn

Index: ui/gfx/x/BUILD.gn
diff --git a/ui/gfx/x/BUILD.gn b/ui/gfx/x/BUILD.gn
deleted file mode 100644
index 23d6536e9163d4a8684974ef6a0ef27bd9ee8136..0000000000000000000000000000000000000000
--- a/ui/gfx/x/BUILD.gn
+++ /dev/null
@@ -1,21 +0,0 @@
-# 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.
-
-component("x") {
-  output_name = "gfx_x11"
-  sources = [
-    "x11_atom_cache.cc",
-    "x11_atom_cache.h",
-    "x11_connection.cc",

[Elliot Glaysher, 2014/05/29 00:06:24]

What happens to this file? It appears to still be in use.

[brettw, 2014/05/29 16:56:34]

Not sure why it was missing from the other one. Added it there.

-    "x11_connection.h",
-    "x11_error_tracker.cc",
-    "x11_error_tracker.h",
-    "x11_types.cc",
-    "x11_types.h",
-  ]
-
-  defines = [ "GFX_IMPLEMENTATION" ]
-  configs += [ "//build/config/linux:x11" ]
-  deps = [ "//base" ]
-}