Examine source code of Yandex Play

{
  "manifest_version": 2,
  "name": "Yandex Play",
  "author": "Pave Goncharov",
  "description": "__MSG_extensionDescription__",
  "version": "1.5.2",
  "default_locale": "en",
  "icons": {
    "64": "icons/play_64.png"
  },
  "options_ui": {
    "page": "settings/settings.html",
    "browser_style": true
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://music.yandex.ru/*"
      ],
      "js": [
        "yamusic.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "64": "icons/play_64.png"
    },
    "default_title": "YaPlay?"
  },
  "commands": {
    "play": {
      "suggested_key": {
        "default": "Alt+2"
      },
      "description": "__MSG_play__/__MSG_pause__"
    },
    "previous": {
      "suggested_key": {
        "default": "Alt+1"
      },
      "description": "__MSG_previous__"
    },
    "next": {
      "suggested_key": {
        "default": "Alt+3"
      },
      "description": "__MSG_next__"
    },
    "mute": {
      "suggested_key": {
        "default": "Alt+4"
      },
      "description": "__MSG_mute__/__MSG_unmute__"
    },
    "volumeUp": {
      "suggested_key": {
        "default": "Alt+5"
      },
      "description": "__MSG_volumeUp__"
    },
    "volumeDown": {
      "suggested_key": {
        "default": "Alt+6"
      },
      "description": "__MSG_volumeDown__"
    },
    "copyLink": {
      "suggested_key": {
        "default": "Alt+7"
      },
      "description": "__MSG_copyLinkToSong__"
    }
  },
  "applications": {
    "gecko": {
      "id": "hacpatb@inbox.ru"
    }
  },
  "permissions": [
    "notifications",
    "tabs",
    "contextMenus",
    "activeTab",
    "clipboardWrite",
    "<all_urls>"
  ]
}