Examine source code of FireLens

{
  "manifest_version": 2,
  "name": "FireLens",
  "description": "Visual impairment simulation and tab-tracker tool to develop for accessibility.",
  "version": "0.0.7",
  "devtools_page": "main.html",
  "web_accessible_resources": [
    "main.html",
    "panel.html",
    "tracer/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icons/firelens-48.png",
    "128": "icons/firelens-128.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/firelens-48.png",
      "128": "icons/firelens-128.png"
    }
  },
  "content_security_policy": "script-src 'self'; font-src 'self' data:; connect-src 'self'; default-src 'self'; frame-src 'self'; img-src 'self' data:; style-src 'self' 'unsafe-inline'",
  "permissions": [
    "tabs",
    "<all_urls>",
    "activeTab"
  ]
}