Examine source code of SaveToImage

{
  "manifest_version": 2,
  "name": "SaveToImage",
  "version": "1.0",
  "description": "A firefox extension to allow you to save images in an specific format.",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "permissions": [
    "contextMenus",
    "downloads",
    "<all_urls>",
    "activeTab",
    "notifications",
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentScript.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "Save To PNG",
    "default_popup": "popup/popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a84933ce-1626-44b8-9b0b-5241dc5ff523}"
    }
  }
}