Examine source code of Download by Free Download Manager

{
  "manifest_version": 2,
  "version": "0.1.3resigned1",
  "name": "Download by Free Download Manager",
  "description": "Optionally use Free Download Manager instead of the built-in download manager to get large files",
  "icons": {
    "16": "data/icons/16.png",
    "19": "data/icons/19.png",
    "32": "data/icons/32.png",
    "38": "data/icons/38.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png",
    "256": "data/icons/256.png"
  },
  "homepage_url": "http://add0n.com/download-by.html",
  "offline_enabled": true,
  "permissions": [
    "storage",
    "notifications",
    "webRequest",
    "webRequestBlocking",
    "nativeMessaging",
    "contextMenus",
    "downloads",
    "*://*/*"
  ],
  "background": {
    "scripts": [
      "core/webext/utils/EventEmitter.js",
      "core/webext/core/base.js",
      "core/webext/core/chrome.storage.js",
      "core/webext/core/chrome.runtime.js",
      "core/webext/core/chrome.notifications.js",
      "core/webext/core/chrome.browserAction.js",
      "core/webext/core/chrome.contextMenus.js",
      "core/webext/core/chrome.tabs.js",
      "core/background.js",
      "termlib_parser.js",
      "config.js",
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "data/icons/disabled/16.png",
      "18": "data/icons/disabled/18.png",
      "19": "data/icons/disabled/19.png",
      "32": "data/icons/disabled/32.png",
      "36": "data/icons/disabled/36.png",
      "38": "data/icons/disabled/38.png",
      "48": "data/icons/disabled/48.png",
      "64": "data/icons/disabled/64.png"
    }
  },
  "options_ui": {
    "page": "data/options/index.html",
    "chrome_style": true
  },
  "applications": {
    "gecko": {
      "id": "{f58cf83a-497b-4f4b-a8ee-13d70fad1fe5}",
      "strict_min_version": "59.0"
    }
  }
}