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

content/content_tests.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.
 
 {
   'targets': [
     {
       'target_name': 'test_support_content',
       'type': 'static_library',
       'defines!': ['CONTENT_IMPLEMENTATION'],
@@ skipping 776 matching lines @@
               'dependencies': [
                 # Runtime dependencies
                 '../webkit/webkit.gyp:copy_npapi_test_plugin',
                 '../webkit/webkit.gyp:pull_in_copy_TestNetscapePlugIn',
               ],
             }],
           ],
         },
       ],
     }],
-    ['chromeos==1 or OS=="linux" or OS=="win" or OS=="mac"', {
+    ['chromeos==1 or OS=="win" or OS=="mac"', {
       'targets': [
           {
             'target_name': 'video_decode_accelerator_unittest',
             'type': 'executable',
             'dependencies': [
               'content',
               '../base/base.gyp:base',
               '../testing/gtest.gyp:gtest',
               '../media/media.gyp:media',
               '../ui/ui.gyp:ui',
@@ skipping 121 matching lines @@
             'resource_dir': '../res',
             'additional_src_dirs': ['../content/public/android/javatests/'],
             'is_test_apk': 1,
           },
           'includes': [ '../build/java_apk.gypi' ],
         },
       ],
     }],
   ],
 }