Remove MediaControls methods needed for the Cast button

third_party/WebKit/Source/modules/remoteplayback/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("//third_party/WebKit/Source/modules/modules.gni")
 
 blink_modules_sources("remoteplayback") {
   sources = [
+    "AvailabilityCallbackWrapper.cpp",
+    "AvailabilityCallbackWrapper.h",
     "HTMLMediaElementRemotePlayback.cpp",
     "HTMLMediaElementRemotePlayback.h",
     "RemotePlayback.cpp",
     "RemotePlayback.h",
   ]
 }