Examine source code of Weaselspark Extension

{
  "manifest_version": 2,
  "name": "Weaselspark Extension",
  "version": "0.4",
  "icons": {
    "16": "icons/icon-16px.png",
    "48": "icons/icon-48px.png",
    "128": "icons/icon-128px.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16px.png",
      "24": "icons/icon-24px.png",
      "32": "icons/icon-32px.png"
    },
    "default_title": "Cliquez pour créer un weasel"
  },
  "permissions": [
    "<all_urls>",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "libs/browser-polyfill.min.js",
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "libs/browser-polyfill.min.js",
        "content.js"
      ],
      "run_at": "document_start"
    }
  ]
}