Do not compile third_party/libva on Linux. It's not used.

content/content_common.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.
 
 {
   'dependencies': [
     '../base/base.gyp:base',
     '../build/temp_gyp/googleurl.gyp:googleurl',
     '../media/media.gyp:media',
     '../net/net.gyp:net',
@@ skipping 471 matching lines @@
         '<(DEPTH)/third_party/angle/include',
         '<(DEPTH)/third_party/openmax/il',
       ],
       'link_settings': {
         'libraries': [
           '-lEGL',
           '-lGLESv2',
         ],
       },
     }],
-    ['target_arch != "arm" and (OS=="linux" or chromeos == 1)', {
+    ['target_arch != "arm" and chromeos == 1', {
       'sources': [
         'common/gpu/media/h264_dpb.cc',
         'common/gpu/media/h264_dpb.h',
         'common/gpu/media/vaapi_h264_decoder.cc',
         'common/gpu/media/vaapi_h264_decoder.h',
         'common/gpu/media/vaapi_video_decode_accelerator.cc',
         'common/gpu/media/vaapi_video_decode_accelerator.h',
       ],
       'include_dirs': [
         '<(DEPTH)/third_party/libva',
@@ skipping 55 matching lines @@
         '../build/extract_from_cab.py',
         '..\\third_party\\directxsdk\\files\\Redist\\<(input)',
         '<(output)',
         '<(PRODUCT_DIR)',
         ],
       },
      ]
     }],
   ],
 }