Examine source code of MaxFocus: Link Preview

{
  "manifest_version": 2,
  "name": "__MSG_appName__",
  "description": "__MSG_appDesc__",
  "version": "0.5.8",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "declarativeNetRequest",
    "storage",
    "contextMenus",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "sidebarAction",
    "*://*/*"
  ],
  "default_locale": "en",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "sidebar_action": {
    "default_panel": "sidepanel.html",
    "default_title": "Document",
    "open_at_install": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "run_at": "document_start",
      "js": [
        "content-scripts/content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "content-scripts/content.css"
  ],
  "browser_action": {},
  "browser_specific_settings": {
    "gecko": {
      "id": "{4bda55a4-25fc-4958-aca3-4b3261605398}"
    }
  }
}