Revert of Deletes mojo::Callback

components/mus/clipboard/BUILD.gn

 # Copyright 2016 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.
 
 import("//mojo/public/mojo_application.gni")
 import("//mojo/public/mojo_application_manifest.gni")
 import("//testing/test.gni")
 
 source_set("lib") {
   sources = [
     "clipboard_impl.cc",
     "clipboard_impl.h",
   ]
 
   deps = [
     "//base",
     "//components/mus/public/interfaces",
     "//mojo/common",
     "//mojo/public/cpp/bindings",
+    "//mojo/public/cpp/bindings:callback",
     "//services/shell/public/cpp",
     "//services/tracing/public/cpp",
   ]
 }
 
 group("tests") {
   testonly = true
   deps = [
     ":mus_clipboard_unittests",
   ]
@@ skipping 18 matching lines @@
     ":lib",
     "//components/mus:mus",
   ]
 }
 
 mojo_application_manifest("test_manifest") {
   type = "exe"
   application_name = "mus_clipboard_unittests"
   source = "test_manifest.json"
 }