LayoutTests/media/media-source/content/test-vp9-manifest.json

{
	"url": "content/test-vp9.webm",
	"type": "video/webm; codecs=\"vp09.00.10.08\"",
	"init": { "offset": 0, "size": 629 },
	"duration": 2,
	"media": [ 
		{ "offset": 629, "size": 43724, "timestamp": 0, "duration": 2}
	]
}