Rename "test" ozone platform to "headless"

ui/ozone/platform/test/BUILD.gn

Index: ui/ozone/platform/test/BUILD.gn
diff --git a/ui/ozone/platform/test/BUILD.gn b/ui/ozone/platform/test/BUILD.gn
deleted file mode 100644
index 2148d7b34fceb8c43a2797eaf9f230cb01bade8d..0000000000000000000000000000000000000000
--- a/ui/ozone/platform/test/BUILD.gn
+++ /dev/null
@@ -1,27 +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.
-
-source_set("test") {
-  sources = [
-    "client_native_pixmap_factory_test.cc",
-    "client_native_pixmap_factory_test.h",
-    "ozone_platform_test.cc",
-    "ozone_platform_test.h",
-    "test_surface_factory.cc",
-    "test_surface_factory.h",
-    "test_window.cc",
-    "test_window.h",
-    "test_window_manager.cc",
-    "test_window_manager.h",
-  ]
-
-  deps = [
-    "//base",
-    "//skia",
-    "//ui/base",
-    "//ui/gfx/geometry",
-    "//ui/events/ozone:events_ozone_layout",
-    "//ui/events/platform",
-  ]
-}