[Cast] Consolidate plethora of GYP files into cast.gyp and cast_testing.gypi.

media/cast/cast_sender.gyp

-# Copyright 2013 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.
-
-{
-  'variables': {
-    'chromium_code': 1,
-  },
-  'includes': [
-    'audio_sender/audio_sender.gypi',
-    'congestion_control/congestion_control.gypi',
-    'video_sender/video_sender.gypi',
-  ],
-  'targets': [
-    {
-      'target_name': 'cast_sender',
-      'type': 'static_library',
-      'include_dirs': [
-        '<(DEPTH)/',
-      ],
-      'sources': [
-        'cast_sender.h',
-        'cast_sender_impl.cc',
-        'cast_sender_impl.h',
-      ], # source
-      'dependencies': [
-        '<(DEPTH)/media/cast/transport/cast_transport.gyp:cast_transport',
-        'audio_sender',
-        'congestion_control',
-        'rtcp/rtcp.gyp:cast_rtcp',
-        'video_sender',
-      ], # dependencies
-    },
-  ],
-}