Revert of Implement ui::ClipboardMus.

ui/base/clipboard/custom_data_helper_linux.cc

Index: ui/base/clipboard/custom_data_helper_linux.cc
diff --git a/ui/base/clipboard/custom_data_helper_linux.cc b/ui/base/clipboard/custom_data_helper_linux.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d8cc89edff558d052a49bd61121b7e58301aa0aa
--- /dev/null
+++ b/ui/base/clipboard/custom_data_helper_linux.cc
@@ -0,0 +1,13 @@
+// Copyright (c) 2011 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.
+
+#include "build/build_config.h"
+#include "ui/base/clipboard/custom_data_helper.h"
+
+namespace ui {
+
+// TODO(dcheng): This name is temporary. See crbug.com/106449
+const char kMimeTypeWebCustomData[] = "chromium/x-web-custom-data";
+
+}  // namespace ui