CastContentBrowserClient should not hold CastBrowserMainParts lifetime.

chromecast/chromecast.gyp

-# Copyright 2014 The Chromium Authors. All Rights Reserved.
+# 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'chromecast_branding%': 'Chromium',
   },
   'target_defaults': {
     'include_dirs': [
@@ skipping 170 matching lines @@
             '<@(_outputs)',
           ],
           'includes': [
             '../build/util/version.gypi',
           ],
         },
       ],
     },
   ],  # end of targets
 }