Motown: Convert MediaSink to expose MediaTimelineControlSite

mojo/services/media/common/interfaces/BUILD.gn

 # 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.
 
 import("//build/module_args/mojo.gni")
 import("$mojo_sdk_root/mojo/public/tools/bindings/mojom.gni")
 
 mojom("interfaces") {
   sources = [
     "media_common.mojom",
     "media_metadata.mojom",
-    "media_state.mojom",
     "media_transport.mojom",
     "media_types.mojom",
     "timelines.mojom",
   ]
 }