Examine source code of Tab Marker – Labels & Colors

{
  "manifest_version": 2,
  "name": "Tab Labeler",
  "version": "1.0.0",
  "description": "Give custom names and colors to individual tabs. Shows a small label at the top of the page.",
  "browser_action": {
    "default_title": "Tab Labeler",
    "default_popup": "popup.html"
  },
  "permissions": [
    "tabs",
    "storage",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentScript.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d519e7b3-6ca5-4e4a-8965-5b7e02c10b1f}"
    }
  }
}