Examine source code of Ad Observer

{
  "homepage_url": "https://adobserver.org",
  "icons": {
    "16": "assets/icon16.png",
    "32": "assets/icon32.png",
    "48": "assets/icon48.png",
    "64": "assets/icon64.png",
    "128": "assets/icon128.png"
  },
  "manifest_version": 2,
  "name": "Ad Observer",
  "short_name": "Ad Observer",
  "description": "A browser extension to share data about your social feed with researchers and journalists to increase transparency.",
  "version": "3.2.14",
  "version_name": "3.2.14 (9a276f4)",
  "default_locale": "en",
  "content_scripts": [
    {
      "js": [
        "preload/bundle.js"
      ],
      "matches": [
        "*://*.facebook.com/*"
      ],
      "exclude_globs": [
        "*://*.facebook.com/ads/archive*",
        "*://*.facebook.com/ads/library*"
      ],
      "run_at": "document_start"
    },
    {
      "js": [
        "ytpreload/bundle.js"
      ],
      "matches": [
        "*://www.youtube.com/*"
      ],
      "run_at": "document_start"
    },
    {
      "js": [
        "content/bundle.js"
      ],
      "matches": [
        "*://*.facebook.com/*",
        "*://www.youtube.com/*"
      ],
      "exclude_globs": [
        "*://*.facebook.com/ads/archive*",
        "*://*.facebook.com/ads/library*"
      ],
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "bundle.js"
    ]
  },
  "permissions": [
    "storage",
    "unlimitedStorage"
  ],
  "web_accessible_resources": [
    "webpage/*",
    "assets/runs_on_fb.js",
    "assets/runs_on_yt.js"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "browser_action": {
    "default_popup": "toolbar/index.html",
    "default_icon": "assets/icon128.png",
    "default_title": "Ad Observer"
  },
  "applications": {
    "gecko": {
      "id": "developers@adobserver.org"
    }
  }
}