Examine source code of DoubleClickSearch

{
  "manifest_version": 2,
  "name": "DoubleClickSearch",
  "version": "2.0.2",
  "author": "kppk05",
  "description": "Search selected text by double click.",
  "homepage_url": "https://addons.mozilla.org/ja/firefox/addon/doubleclicksearch/",
  "icons": {
    "64": "icons/icon-doubleclicksearch-64.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content-scripts/content-doubleclicksearch.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background-scripts/background-doubleclicksearch.js"
    ]
  },
  "permissions": [
    "tabs"
  ]
}