Examine source code of g2tweet

{
  "manifest_version": 2,
  "name": "g2tweet",
  "version": "0.1.2",
  "description": "Let's you tweet your Google search query to Twitter",
  "icons": {
    "48": "icons/g2t-48.png"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "include_globs": [
        "*://*.google.*/*"
      ],
      "js": [
        "g2tweet.js"
      ]
    }
  ]
}