Cleanup: no need to redeclare use_system_yasm.

ffmpeg.gyp

 # Copyright (c) 2011 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.
 
 # There's a couple key GYP variables that control how FFmpeg is built:
 #   ffmpeg_branding
 #     Controls whether we build the Chromium or Google Chrome version of
 #     FFmpeg.  The Google Chrome version contains additional codecs.
 #     Typical values are Chromium, Chrome, ChromiumOS, and ChromeOS.
 #   use_system_ffmpeg
@@ skipping 48 matching lines @@
       ['chromeos==1', {
         'ffmpeg_branding%': '<(branding)OS',
       }, {  # otherwise, assume Chrome/Chromium.
         'ffmpeg_branding%': '<(branding)',
       }],
     ],
 
     'ffmpeg_variant%': '<(target_arch)',
 
     'use_system_ffmpeg%': 0,
-    'use_system_yasm%': 0,
     'build_ffmpegsumo%': 1,
 
     # Locations for generated artifacts.
     'shared_generated_dir': '<(SHARED_INTERMEDIATE_DIR)/third_party/ffmpeg',
     'asm_library': 'ffmpegasm',
   },
   'conditions': [
     ['OS!="win" and use_system_ffmpeg==0 and build_ffmpegsumo!=0', {
       'targets': [
         {
@@ skipping 448 matching lines @@
       ],  # conditions
     },
   ],  # targets
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: