Examine source code of Mass Finder

{
  "manifest_version": 2,
  "name": "Mass Finder",
  "version": "1.1",
  "description": "Easy Mass... Assignment",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "<all_urls>",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "devtools_page": "devtools/devtools.html",
  "icons": {
    "48": "icons/mass48.png",
    "96": "icons/mass96.png",
    "128": "icons/mass128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d5181b21-01b9-4fcc-b636-2b32364b58bf}"
    }
  }
}