Examine source code of eff-screenshots

{
  "manifest_version": 2,
  "name": "eff-screenshots",
  "version": "1.0",
  "description": "Takes a screenshot of the current active tab.",
  "icons": {
    "64": "icons/icon.png"
  },
  "browser_action": {
    "default_icon": {
      "64": "icons/icon.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "<all_urls>",
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}