Examine source code of Search Everyday

{
  "omnibox": {
    "keyword": "!"
  },
  "description": "Access the internet with custom web search powered by Yahoo!(R) from your browser search bar.",
  "icons": {
    "128": "icons/icon128.png"
  },
  "version": "2.8.3.11",
  "web_accessible_resources": [
    "pages/*"
  ],
  "browser_action": {
    "default_icon": "icons/icon128.png",
    "default_popup": "popup/popup.html"
  },
  "permissions": [
    "cookies",
    "contextMenus",
    "storage",
    "*://*.searcheveryday.co/*"
  ],
  "background": {
    "scripts": [
      "js/common.js",
      "js/background.js"
    ]
  },
  "manifest_version": 2,
  "name": "Search Everyday",
  "content_scripts": [
    {
      "matches": [
        "*://*.search.yahoo.com/*"
      ],
      "js": [
        "js/common.js",
        "js/content-yahoo.js"
      ],
      "run_at": "document_end"
    }
  ],
  "chrome_settings_overrides": {
    "search_provider": {
      "favicon_url": "https://www.searcheveryday.co/favicon.ico",
      "search_url": "https://search.yahoo.com/yhs/search?hspart=sz&hsimp=yhs-001&type=type7018630-sv7-66424-69467&param1=66424&p={searchTerms}&param2=69467",
      "suggest_url": "https://search.yahoo.com/sugg/ie?output=fxjson&command={searchTerms}&nResults=10",
      "name": "Search Everyday's custom search powered by Yahoo",
      "keyword": "Yahoo",
      "encoding": "UTF-8",
      "is_default": true
    }
  },
  "applications": {
    "gecko": {
      "strict_min_version": "65.0",
      "id": "{c8140ae6-f6d5-40dc-8a1b-13219a3e9837}"
    }
  }
}