ffmpeg_unittests should depend on use_ffmpeg==1

media/media.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
     # Override to dynamically link the PulseAudio library.
     'use_pulseaudio%': 0,
     # Override to dynamically link the cras (ChromeOS audio) library.
@@ skipping 1374 matching lines @@
             '../base/base.gyp:base',
           ],
           'variables': {
             'java_in_dir': 'base/android/java',
           },
           'includes': [ '../build/java.gypi' ],
         },
 
       ],
     }],
-    ['OS != "android" and OS != "ios"', {
-      # Android and iOS do not use ffmpeg, so disable the targets which require
-      # it.
+    ['use_ffmpeg == 1', {
       'targets': [
         {
           'target_name': 'ffmpeg_unittests',
           'type': 'executable',
           'dependencies': [
             '../base/base.gyp:base',
             '../base/base.gyp:base_i18n',
             '../base/base.gyp:test_support_base',
             '../base/base.gyp:test_support_perf',
             '../testing/gtest.gyp:gtest',
@@ skipping 99 matching lines @@
           ],
           'sources': [
             'video/capture/screen/differ_block_sse2.cc',
             'video/capture/screen/differ_block_sse2.h',
           ],
         }, # end of target differ_block_sse2
       ],
     }],
   ],
 }