Examine source code of Enhancer for Startpage

{
  "manifest_version": 2,
  "name": "Enhancer for Startpage",
  "version": "4.0",
  "description": "Enhance your Startpage experience with a custom theme and centered search results!",
  "icons": {
    "582": "icons/search-icon-purple-background.png"
  },
  "chrome_settings_overrides": {
    "search_provider": {
      "name": "Startpage",
      "keyword": "@startpage",
      "search_url": "https://www.startpage.com/sp/search?query={searchTerms}",
      "is_default": true,
      "encoding": "UTF-8"
    }
  },
  "background": {
    "scripts": [
      "src/background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_icon": "icons/search-icon-purple-background.png",
    "default_title": "Toggle Theme",
    "default_popup": "src/popup.html"
  },
  "permissions": [
    "storage",
    "activeTab",
    "webNavigation"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.startpage.com/*"
      ],
      "js": [
        "src/browserAPI.js",
        "src/theme.js",
        "src/delay.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{835f366a-0210-4f68-8044-5216d411fb1e}"
    }
  }
}