Remove som GYP annotations, remove unused manifest.

chromecast/media/cdm/BUILD.gn

 # 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.
 
 import("//chromecast/chromecast.gni")
 
-# GYP target: chromecast/media.gyp:media_cdm
 source_set("cdm") {
   sources = [
     "cast_cdm.cc",
     "cast_cdm.h",
     "cast_cdm_context.cc",
     "cast_cdm_context.h",
     "cast_cdm_proxy.cc",
     "cast_cdm_proxy.h",
     "chromecast_init_data.cc",
     "chromecast_init_data.h",
@@ skipping 10 matching lines @@
 
   if (is_android && use_playready) {
     sources += [
       "playready_drm_delegate_android.cc",
       "playready_drm_delegate_android.h",
     ]
 
     deps += [ "//media/base/android" ]
   }
 }