Examine source code of BeLearn

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "BeLearn",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "icons": {
    "48": "images/belearn-48.png",
    "128": "images/belearn-128.png"
  },
  "browser_action": {
    "default_icon": {
      "19": "images/belearn-19.png",
      "38": "images/belearn-38.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{7e85e01b-ccaf-4fd8-b11f-6da851c5e384}"
    }
  }
}