Examine source code of devtools-outliner

{
  "description": "DevTools Inspector sidebar panel to outline elements",
  "manifest_version": 2,
  "name": "devtools-outliner",
  "version": "1.0.1resigned1",
  "author": "Patrick Brosset",
  "homepage_url": "https://github.com/captainbrosset/devtools-outliner",
  "icons": {
    "48": "icons/logo.svg"
  },
  "permissions": [
    "<all_urls>"
  ],
  "devtools_page": "devtools/devtools-page.html",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "content_scripts/content.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f85aad15-c9c5-49e6-8452-31115c9f2739}"
    }
  }
}