Examine source code of RTF Viewer

{
  "manifest_version": 2,
  "name": "RTF Viewer",
  "description": "Display .rtf (Rich Text Format) files in the browser",
  "version": "1.4.2",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "applications": {
    "gecko": {
      "strict_min_version": "56.0"
    }
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/icon16.png"
    }
  },
  "background": {
    "scripts": [
      "background.js",
      "rtfRedirectHandler.js"
    ]
  },
  "incognito": "spanning",
  "web_accessible_resources": [
    "viewer/viewer.html"
  ]
}