Examine source code of RSSPreview

{
  "manifest_version": 2,
  "name": "RSSPreview",
  "version": "4.0",
  "author": "Aurelien David",
  "homepage_url": "https://github.com/aureliendavid/rsspreview",
  "description": "Preview RSS feeds in browser",
  "icons": {
    "32": "icons/rss-32.png",
    "48": "icons/rss-48.png",
    "64": "icons/rss-64.png",
    "128": "icons/rss-128.png",
    "256": "icons/rss-256.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "rsspreview.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "preview.css",
    "rss.xsl",
    "icons/*.png",
    "lib/xslt-polyfill.min.js"
  ],
  "options_ui": {
    "page": "settings/options.html"
  },
  "page_action": {
    "browser_style": true,
    "default_icon": {
      "19": "icons/rss-gray-19.png",
      "38": "icons/rss-gray-38.png"
    },
    "default_title": "Feeds in page"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7799824a-30fe-4c67-8b3e-7094ea203c94}"
    },
    "gecko_android": {
      "strict_min_version": "113.0"
    }
  },
  "permissions": [
    "<all_urls>",
    "webRequest",
    "webRequestBlocking",
    "storage",
    "tabs"
  ]
}