Cast:Moving netwrok sender related code to a designated folder

media/cast/net/pacing/paced_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.
 
 {
   'targets': [
     {
       'target_name': 'cast_paced_sender',
       'type': 'static_library',
       'include_dirs': [
         '<(DEPTH)/',
       ],
       'sources': [
         'paced_sender.h',
         'paced_sender.cc',
       ],
       'dependencies': [
         '<(DEPTH)/base/base.gyp:base',
       ],
     },
   ], # targets
 }