Examine source code of SendBouyomiChan

{
  "manifest_version": 2,
  "name": "SendBouyomiChan",
  "description": "選択した文字列を棒読みちゃんに転送します。",
  "version": "0.2.2",
  "author": "toshi",
  "homepage_url": "https://www.bugbugnow.net/",
  "browser_specific_settings": {
    "gecko": {
      "id": "SendBouyomiChan@bugbugnow.net"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "scripting"
  ]
}