Examine source code of Twitch Emotes Extension

{
  "name": "Twitch Emotes Extension",
  "description": "A Twitch extension that replaces keywords with custom emotes.",
  "version": "1.4",
  "manifest_version": 2,
  "icons": {
    "16": "/images/icon-16x16.png",
    "32": "/images/icon-32x32.png",
    "48": "/images/icon-48x48.png",
    "128": "/images/icon-128x128.png"
  },
  "background": {
    "scripts": [
      "./scripts/background.js"
    ]
  },
  "browser_action": {
    "default_popup": "./popup/popup.html"
  },
  "permissions": [
    "<all_urls>",
    "scripting",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ca390c92-5867-4734-a233-da3e5e4848d9}"
    }
  }
}