Examine source code of Yandex Music Controller

{
  "manifest_version": 2,
  "name": "Yandex Music Controller",
  "version": "1.0.1",
  "description": "Управление воспроизведением музыки на music.yandex.ru с помощью горячих клавиш",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "*://music.yandex.ru/*",
    "activeTab",
    "tabs",
    "webNavigation",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js",
      "install.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://music.yandex.ru/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "linkurakt@gmail.com"
    }
  },
  "commands": {
    "play-pause": {
      "suggested_key": {
        "default": "Alt+P"
      },
      "description": "Воспроизведение и пауза"
    },
    "next-track": {
      "suggested_key": {
        "default": "Alt+Right"
      },
      "description": "Следующий трек"
    },
    "prev-track": {
      "suggested_key": {
        "default": "Alt+Left"
      },
      "description": "Предыдущий трек"
    },
    "seek-forward": {
      "suggested_key": {
        "default": "Alt+Shift+Right"
      },
      "description": "Перемотать вперед на 10 секунд"
    },
    "seek-backward": {
      "suggested_key": {
        "default": "Alt+Shift+Left"
      },
      "description": "Перемотать назад на 10 секунд"
    },
    "like-track": {
      "suggested_key": {
        "default": "Alt+L"
      },
      "description": "Отметить как понравившийся"
    },
    "dislike": {
      "suggested_key": {
        "default": "Alt+D"
      },
      "description": "Отметить как не понравившийся"
    },
    "volume-up": {
      "suggested_key": {
        "default": "Alt+Up"
      },
      "description": "Громче"
    },
    "volume-down": {
      "suggested_key": {
        "default": "Alt+Down"
      },
      "description": "Тише"
    },
    "open-player": {
      "suggested_key": {
        "default": "Alt+Z"
      },
      "description": "Открыть плеер"
    }
  },
  "browser_action": {
    "default_icon": {
      "19": "icons/icon-19.png",
      "38": "icons/icon-38.png"
    },
    "default_title": "Yandex Music Controller",
    "default_popup": "popup/popup.html"
  }
}