Add GN build file for ui/aura target.

ui/events/platform/x11/BUILD.gn

Index: ui/events/platform/x11/BUILD.gn
diff --git a/ui/events/platform/x11/BUILD.gn b/ui/events/platform/x11/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..6c8bbe4b1f250e1e600193127353aade3d25409e
--- /dev/null
+++ b/ui/events/platform/x11/BUILD.gn
@@ -0,0 +1,42 @@
+# 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("x11") {
+  output_name = "x11_events_platform"
+
+  sources = [
+    "x11_event_source.cc",
+    "x11_event_source.h",
+    "x11_event_source_glib.cc",
+    "x11_event_source_libevent.cc",
+  ]
+
+  defines = [
+    "EVENTS_IMPLEMENTATION",
+  ]
+
+  configs += [
+    "//build/config/linux:x11",
+  ]
+
+  deps = [
+    "//ui/events",
+    "//ui/events/platform",
+    "//ui/gfx/x",
+  ]
+
+  if (is_linux) {
+    sources -= [
+      "x11_event_source_libevent.cc",
+    ]
+
+    configs += [
+      "//build/config/linux:glib",
+    ]
+  } else {
+    sources -= [
+      "x11_event_source_glib.cc",
+    ]
+  }
+}