Examine source code of vk_music

{
  "manifest_version": 2,
  "name": "vk_music",
  "version": "1.0.2resigned1",
  "desription": "Allows to control vk music player from any tab",
  "icons": {
    "48": "icons/vk-48.png"
  },
  "permissions": [
    "tabs",
    "*://*.vk.com/*"
  ],
  "browser_action": {
    "default_icon": "icons/vk-32.png",
    "default_title": "vk_music",
    "default_popup": "popup/player.html"
  },
  "background": {
    "scripts": [
      "/background_scripts/hotkeys_handler.js"
    ]
  },
  "commands": {
    "prev": {
      "suggested_key": {
        "default": "Alt+Shift+J"
      },
      "description": "Play previous track"
    },
    "play": {
      "suggested_key": {
        "default": "Alt+Shift+K"
      },
      "description": "Toggle between play and pause"
    },
    "next": {
      "suggested_key": {
        "default": "Alt+Shift+L"
      },
      "description": "Play next track"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{aafa9a4e-6e99-48e5-aa4f-0b62ea1b9b61}"
    }
  }
}