Examine source code of Spotifyx2 V2.3 - x2 ( HxN )

{
  "name": "Spotifx2",
  "description": "Keyboard shortcuts to play, pause, next and previous tracks in Spotify Web Player.",
  "manifest_version": 2,
  "author": "x2",
  "version": "2.3",
  "icons": {
    "128": "icons/logo-128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://open.spotify.com/*",
        "https://play.spotify.com/*"
      ],
      "js": [
        "notifications.js"
      ],
      "run_at": "document_end"
    }
  ],
  "commands": {
    "play-pause": {
      "suggested_key": {
        "default": "Alt+Shift+W"
      },
      "description": "Play/pause the current song"
    },
    "next": {
      "suggested_key": {
        "default": "Alt+Shift+Right"
      },
      "description": "Next track"
    },
    "previous": {
      "suggested_key": {
        "default": "Alt+Shift+Left"
      },
      "description": "Previous track"
    },
    "shuffle": {
      "suggested_key": {
        "default": "Alt+Shift+D"
      },
      "description": "Shuffle playlist"
    },
    "repeat": {
      "suggested_key": {
        "default": "Alt+Shift+R"
      },
      "description": "Repeat playlist"
    },
    "play-album": {
      "suggested_key": {
        "default": "Alt+Shift+G"
      },
      "description": "Play/pause the current playlist/album"
    },
    "save-track": {
      "suggested_key": {
        "default": "Alt+Shift+L"
      },
      "description": "Save track"
    },
    "mute": {
      "suggested_key": {
        "default": "Alt+Shift+M"
      },
      "description": "Mute/Unmute"
    },
    "volume-up": {
      "suggested_key": {
        "default": "Alt+Shift+Up"
      },
      "description": "Volume up"
    },
    "volume-down": {
      "suggested_key": {
        "default": "Alt+Shift+Down"
      },
      "description": "Volume down"
    }
  },
  "permissions": [
    "https://open.spotify.com/*",
    "https://play.spotify.com/*",
    "tabs",
    "storage",
    "notifications"
  ],
  "browser_action": {
    "default_icon": "icons/logo-128.png",
    "theme_icons": [
      {
        "light": "icons/logo-32-light.png",
        "dark": "icons/logo-32.png",
        "size": 32
      }
    ],
    "default_title": "Spotify",
    "default_popup": "panel/panel.html"
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{691b0c15-6ed8-412f-ab4e-c64f6d8d6ef0}"
    }
  }
}