Examine source code of safer-links

{
  "manifest_version": 2,
  "name": "My Extension",
  "description": "Block the .zip and .mov domains",
  "version": "1.0",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon.png",
      "48": "icon.png",
      "128": "icon.png"
    }
  },
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  },
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5a749968-fc2c-464e-80c4-1a3e7ca6816e}"
    }
  }
}