Examine source code of Page Load Progress

{
  "manifest_version": 2,
  "name": "Page Load Progress",
  "version": "1.0.1",
  "description": "Shows a subtle progress bar with detailed loading information at the top of web pages",
  "icons": {
    "96": "icon.png"
  },
  "permissions": [
    "webRequest",
    "webNavigation",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "progress.css"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "page-load-progress@John",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "developer": {
    "name": "John",
    "url": "https://none.us"
  },
  "homepage_url": "https://none.us"
}