to get this working on a mac trying using this:
{
    "version": "0.1.0",
    "command": "Chrome",
    "osx": {
        "command": "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome"
    },
    "args": [
        "${file}"
    ]
}
If you have chrome already open, it will launch your html file in a new tab.