Examine source code of Yandex Music Player

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "version": "1.2.1",
  "default_locale": "en",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "applications": {
    "gecko": {
      "id": "ymc@dzhard.github.org",
      "strict_min_version": "57.0"
    }
  },
  "permissions": [
    "*://music.yandex.ru/*",
    "*://music.yandex.by/*",
    "*://music.yandex.com/*",
    "*://music.yandex.kz/*",
    "*://music.yandex.ua/*",
    "activeTab",
    "tabs",
    "notifications",
    "storage",
    "contextMenus"
  ],
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "__MSG_extensionName__",
    "default_popup": "popup/controls.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://music.yandex.ru/*",
        "*://music.yandex.by/*",
        "*://music.yandex.com/*",
        "*://music.yandex.kz/*",
        "*://music.yandex.ua/*"
      ],
      "js": [
        "injector.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "hotKeyHandler.js",
      "contextMenu.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "yamusic@dzhard.github.com",
      "strict_min_version": "57.0"
    }
  },
  "commands": {
    "play-pause": {
      "suggested_key": {
        "default": "Alt+P"
      },
      "description": "Play/Pause"
    },
    "next": {
      "suggested_key": {
        "default": "Alt+W"
      },
      "description": "Next"
    },
    "prev": {
      "suggested_key": {
        "default": "Alt+Q"
      },
      "description": "Previous"
    }
  }
}