Examine source code of SwanSearch

{
  "name": "SwanSearch",
  "version": "0.9.0",
  "manifest_version": 2,
  "description": "2x faster web search. Get 'Smart Preview' for each result, saves your time for the actual work.",
  "homepage_url": "https://kambanthemaker.com",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "default_locale": "en",
  "background": {
    "scripts": [
      "src/bg/fdb-all.min.js",
      "src/bg/background.js"
    ],
    "persistent": true
  },
  "options_page": "src/options_custom/index.html",
  "browser_action": {
    "default_icon": "icons/icon19.png",
    "default_title": "page action demo",
    "default_popup": "src/page_action/page_action.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://google.com/*",
        "*://duckduckgo.com/*",
        "*://www.duckduckgo.com/*",
        "*://bing.com/*",
        "*://www.bing.com/*"
      ],
      "js": [
        "src/content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "icons/*"
  ],
  "permissions": [
    "activeTab",
    "tabs",
    "*://google.com/*",
    "*://www.google.com/*",
    "*://duckduckgo.com/*",
    "*://www.duckduckgo.com/*",
    "*://bing.com/*",
    "*://www.bing.com/*",
    "webNavigation"
  ]
}