Examine source code of GetImageinfo plus

{
  "name": "GetImageinfo",
  "version": "1.0.1",
  "description": "Get image info for images, including EXIF data",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "contextMenus",
    "tabs",
    "http://*/*",
    "https://*/*"
  ],
  "minimum_chrome_version": "6.0.0.0",
  "icons": {
    "16": "imageinfo-16.png",
    "48": "imageinfo-48.png",
    "128": "imageinfo-128.png"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{b281b003-fd73-4fe6-8eba-43a5cfd8287f}"
    }
  }
}