Remove //mojo/platform_handle

mojo/platform_handle/BUILD.gn

Index: mojo/platform_handle/BUILD.gn
diff --git a/mojo/platform_handle/BUILD.gn b/mojo/platform_handle/BUILD.gn
deleted file mode 100644
index a3710c9200bfdfdd71e2d2b42b2dcaa1a4bcdc28..0000000000000000000000000000000000000000
--- a/mojo/platform_handle/BUILD.gn
+++ /dev/null
@@ -1,17 +0,0 @@
-# Copyright 2015 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.
-
-# TODO(rockot): Remove this file. It's just a few dummy targets to avoid
-# updating lots of build files in the platform handle API change.
-
-group("platform_handle") {
-}
-group("platform_handle_impl") {
-}
-group("platform_handle_thunks") {
-}
-group("for_shared_library") {
-}
-group("for_component") {
-}