Examine source code of Comfortable Search

{
  "manifest_version": 2,
  "name": "Comfortable Search",
  "short_name": "Comfortable Search",
  "description": "Делает поиск чище и удобнее.",
  "version": "0.2resigned1",
  "icons": {
    "16": "images/icon_search_16.png",
    "48": "images/icon_search_16.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "https://www.google.ru/*",
    "https://www.google.com/*",
    "https://stackoverflow.com/search*",
    "https://www.yandex.ru/search/*",
    "https://yandex.ru/search/*",
    "http://qaru.site/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "lib/inject_google.js"
      ],
      "matches": [
        "https://www.google.ru/*",
        "https://www.google.com/*"
      ],
      "run_at": "document_start"
    },
    {
      "all_frames": true,
      "js": [
        "lib/inject_stackoverflow.js"
      ],
      "matches": [
        "https://stackoverflow.com/search*"
      ],
      "run_at": "document_end"
    },
    {
      "all_frames": true,
      "js": [
        "lib/inject_yandex.js"
      ],
      "matches": [
        "https://www.yandex.ru/search/*",
        "https://yandex.ru/search/*"
      ],
      "run_at": "document_end"
    }
  ],
  "options_ui": {
    "open_in_tab": true,
    "chrome_style": true,
    "page": "options.html"
  },
  "browser_action": {
    "default_icon": {
      "16": "images/icon_search_16.png"
    },
    "default_title": "Comfortable Search"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{08da1543-9515-4b14-9f27-9c5c41d6c357}"
    }
  }
}