Examine source code of Amazon Smile Helper

{
  "description": "Verifies if amazon.com is signed-in and if so redirects to smile.amazon.com to ensure purchases count towards the %0.5 donation to a charity of your choice.",
  "manifest_version": 2,
  "name": "Amazon Smile Helper",
  "version": "1.0.1",
  "homepage_url": "https://github.com/dillingspam/AmazonSmileHelper-Firefox",
  "incognito": "spanning",
  "icons": {
    "48": "icons/AutoSmile-48.png",
    "96": "icons/AutoSmile-96.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "cookies",
    "https://www.amazon.com/*"
  ],
  "background": {
    "scripts": [
      "background_script.js"
    ]
  }
}