Examine source code of Alarms & Clock

{
  "name": "__MSG_extName__",
  "version": "1.4resigned1",
  "manifest_version": 2,
  "icons": {
    "32": "res/img/icon32.png",
    "48": "res/img/icon48.png",
    "128": "res/img/icon128.png"
  },
  "default_locale": "en",
  "description": "__MSG_extDesc__",
  "browser_action": {
    "default_title": "__MSG_extName__",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "res/img/icon16.png",
      "24": "res/img/icon24.png",
      "32": "res/img/icon32.png"
    }
  },
  "background": {
    "page": "index.html"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "optional_permissions": [
    "notifications",
    "tabs"
  ],
  "homepage_url": "https://github.com/lmfresneda/clock-alarm-extension",
  "browser_specific_settings": {
    "gecko": {
      "id": "{489e0c4d-1b32-44eb-bbbf-616b6dfc359f}"
    }
  }
}