Add libvpx wrapper to media to support VP9 video decoding.

media/ffmpeg/ffmpeg_common.cc

Index: media/ffmpeg/ffmpeg_common.cc
diff --git a/media/ffmpeg/ffmpeg_common.cc b/media/ffmpeg/ffmpeg_common.cc
index 0aacc5288d1b22bd5256c3b00035034359937045..ac45c55bcf176d6ab1a1f0305d622d7b4fd5d264 100644
--- a/media/ffmpeg/ffmpeg_common.cc
+++ b/media/ffmpeg/ffmpeg_common.cc
@@ -148,6 +148,8 @@ VideoCodec CodecIDToVideoCodec(CodecID codec_id) {
       return kCodecMPEG4;
     case CODEC_ID_VP8:
       return kCodecVP8;
+    case AV_CODEC_ID_VP9:
+      return kCodecVP9;
     default:
       DVLOG(1) << "Unknown video CodecID: " << codec_id;
   }
@@ -168,6 +170,8 @@ static CodecID VideoCodecToCodecID(VideoCodec video_codec) {
       return CODEC_ID_MPEG4;
     case kCodecVP8:
       return CODEC_ID_VP8;
+    case kCodecVP9:
+      return AV_CODEC_ID_VP9;
     default:
       DVLOG(1) << "Unknown VideoCodec: " << video_codec;
   }
@@ -310,7 +314,8 @@ void AVStreamToVideoDecoderConfig(
 
   VideoCodec codec = CodecIDToVideoCodec(stream->codec->codec_id);
   VideoCodecProfile profile = (codec == kCodecVP8) ? VP8PROFILE_MAIN :
-      ProfileIDToVideoCodecProfile(stream->codec->profile);
+      (codec == kCodecVP9) ? VP9PROFILE_MAIN :
+          ProfileIDToVideoCodecProfile(stream->codec->profile);
   gfx::Size natural_size = GetNaturalSize(
       visible_rect.size(), aspect_ratio.num, aspect_ratio.den);
   config->Initialize(codec,