Add chromecast_build gyp variable and add rules when the variable is set to 1.

build/filename_rules.gypi

 # Copyright (c) 2012 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.
 
 # This gypi file defines the patterns used for determining whether a
 # file is excluded from the build on a given platform.  It is
 # included by common.gypi for chromium_code.
 
 {
   'target_conditions': [
@@ skipping 35 matching lines @@
         ['exclude', '_posix(_unittest)?\\.(h|cc)$'],
         ['exclude', '(^|/)posix/'],
       ],
     }],
     ['<(chromeos)!=1 or >(nacl_untrusted_build)==1', {
       'sources/': [
         ['exclude', '_chromeos(_unittest)?\\.(h|cc)$'],
         ['exclude', '(^|/)chromeos/'],
       ],
     }],
+    ['chromecast==0', {
+      'sources/': [
+        ['exclude', '_(cast|chromecast)(_unittest)?\\.(h|cc)$'],

[jam, 2014/04/24 15:38:16]

since after the last meeting we're going to try to not add chromecast files as a
port, but instead use existing or new feature-specific flags, it seems this
isn't necessary anymore?

+      ],
+    }],
     ['>(nacl_untrusted_build)==0', {
       'sources/': [
         ['exclude', '_nacl(_unittest)?\\.(h|cc)$'],
       ],
     }],
     ['OS!="linux" and OS!="openbsd" and OS!="freebsd" or >(nacl_untrusted_build)==1', {
       'sources/': [
         ['exclude', '_xdg(_unittest)?\\.(h|cc)$'],
       ],
     }],
@@ skipping 43 matching lines @@
     ['<(ozone_platform_dri)==0 or >(nacl_untrusted_build)==1', {
       'sources/': [ ['exclude', '_dri(_browsertest|_unittest)?\\.(h|cc)$'],
                     ['exclude', '(^|/)dri/'],
       ]
     }],
     ['<(use_pango)==0', {
       'sources/': [ ['exclude', '(^|_)pango(_util|_browsertest|_unittest)?\\.(h|cc)$'], ],
     }],
   ]
 }