Examine source code of DeezerToolbar

{
  "manifest_version": 2,
  "name": "DeezerToolbar",
  "version": "2.6",
  "description": "Adds a browser action icon to the toolbar to take control of deezer tab.",
  "icons": {
    "48": "Content/play.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "deetoolbar@mozilla.org"
    }
  },
  "browser_action": {
    "default_icon": "Content/deezer-icon.png",
    "default_title": "DeezerToolbar",
    "default_popup": "Popup/DeeCtrl.html"
  },
  "theme_icons": [
    {
      "light": "Content/deezer-icon-sm-light-transparent.png",
      "dark": "Content/deezer-icon-sm-dark-transparent.png",
      "size": 16
    }
  ],
  "options_ui": {
    "page": "Background/options.html"
  },
  "background": {
    "scripts": [
      "Background/background.js",
      "Background/options.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.deezer.com/*"
      ],
      "js": [
        "content_scripts/actions.js"
      ]
    }
  ],
  "permissions": [
    "*://*.deezer.com/*",
    "tabs",
    "storage"
  ],
  "commands": {
    "PrevTrack": {
      "description": "Previous Track",
      "suggested_key": {
        "default": "MediaPrevTrack"
      }
    },
    "NextTrack": {
      "description": "Next Track",
      "suggested_key": {
        "default": "MediaNextTrack"
      }
    },
    "PlayPause": {
      "description": "Play Pause",
      "suggested_key": {
        "default": "MediaPlayPause"
      }
    },
    "Like": {
      "description": "Like",
      "suggested_key": {
        "default": "Ctrl+Shift+L"
      }
    }
  }
}