Examine source code of Elemental 4 Helper

{
  "name": "Elemental 4 Helper",
  "version": "0.3",
  "description": "Convenience features for Elemental 4",
  "permissions": [
    "storage",
    "declarativeContent"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://elemental4.net/*",
        "https://dev.elemental4.net/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "page_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon/icon16.png",
      "32": "icon/icon32.png",
      "48": "icon/icon48.png",
      "128": "icon/icon128.png"
    }
  },
  "icons": {
    "16": "icon/icon16.png",
    "32": "icon/icon32.png",
    "48": "icon/icon48.png",
    "128": "icon/icon128.png"
  },
  "manifest_version": 2
}