Add libvpx wrapper to media to support VP9 video decoding.

media/media.gyp

Index: media/media.gyp
diff --git a/media/media.gyp b/media/media.gyp
index 6d209987416d4d16719bfb300bd06bce64fda5d0..6879847f31b527f87acec32bfd620256d53d7a7e 100644
--- a/media/media.gyp
+++ b/media/media.gyp
@@ -13,8 +13,11 @@
       ['OS == "android" or OS == "ios"', {
         # Android and iOS don't use ffmpeg.
         'use_ffmpeg%': 0,
+        # Android and iOS don't use libvpx.
+        'use_libvpx%': 0,
       }, {  # 'OS != "android" and OS != "ios"'
         'use_ffmpeg%': 1,
+        'use_libvpx%': 1,
       }],
     ],
   },
@@ -314,6 +317,8 @@
         'filters/video_frame_generator.h',
         'filters/video_renderer_base.cc',
         'filters/video_renderer_base.h',
+        'filters/vpx_video_decoder.cc',
+        'filters/vpx_video_decoder.h',
         'video/capture/fake_video_capture_device.cc',
         'video/capture/fake_video_capture_device.h',
         'video/capture/linux/video_capture_device_linux.cc',
@@ -414,6 +419,17 @@
             'webm/webm_stream_parser.h',
           ],
         }],
+        ['use_libvpx == 1', {
+          'dependencies': [
+            '<(DEPTH)/third_party/libvpx/libvpx.gyp:libvpx',
+          ],
+        }, {  # use_libvpx == 0
+          # Exclude the sources that depend on libvpx.
+          'sources!': [
+            'filters/vpx_video_decoder.cc',
+            'filters/vpx_video_decoder.h',
+          ],
+        }],
         ['OS == "ios"', {
           'includes': [
             # For shared_memory_support_sources variable.