Fix V4L2 device failed to create on veyron board

media/media_gpu.gypi

 {
   'variables': {
     'use_v4lplugin%': 0,
     'use_v4l2_codec%': 0,
   },
   'defines': [
     'MEDIA_GPU_IMPLEMENTATION'
   ],
   'dependencies': [
     '../base/base.gyp:base',
@@ skipping 106 matching lines @@
     ['OS=="android" and enable_webrtc==1', {
       'dependencies': [
         '../third_party/libyuv/libyuv.gyp:libyuv',
       ],
       'sources': [
         'gpu/android_video_encode_accelerator.cc',
         'gpu/android_video_encode_accelerator.h',
       ],
     }],
     ['use_v4lplugin==1 and chromeos==1', {
+      'direct_dependent_settings': {

[wuchengli, 2016/05/05 14:36:49]

FYI. content_common.gypi depends on media.gyp:media_gpu (#1). media_gpu target
includes media_gpu.gypi (#2). content_common.gypi needs USE_LIBV4L2 because
content/common/sandbox_linux/bpf_gpu_policy_linux.cc needs it (#3).

#1:
https://code.google.com/p/chromium/codesearch#chromium/src/content/content_co...

#2:
https://code.google.com/p/chromium/codesearch#chromium/src/media/media.gyp&q=...

#3:
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/san...

+        'defines': [
+          'USE_LIBV4L2'
+        ],
+      },
       'defines': [
         'USE_LIBV4L2'
       ],
       'variables': {
         'generate_stubs_script': '../tools/generate_stubs/generate_stubs.py',
         'extra_header': 'gpu/v4l2_stub_header.fragment',
         'sig_files': ['gpu/v4l2.sig'],
         'outfile_type': 'posix_stubs',
         'stubs_filename_root': 'v4l2_stubs',
         'project_path': 'media/gpu',
@@ skipping 217 matching lines @@
       'msvs_settings': {
         'VCCLCompilerTool': {
           'AdditionalOptions': [
             '/wd4267', # Conversion from 'size_t' to 'type', possible loss of data
           ],
         },
       },
     }],
   ],
 }