Examine source code of titlr

{
  "manifest_version": 2,
  "name": "titlr",
  "version": "1.0.0",
  "author": "Giovanni Salinas",
  "description": "Displays a tooltip when the mouse hovers over an element where text overflow is replaced by an ellipsis.",
  "icons": {
    "16": "icons/titlr-16.png",
    "48": "icons/titlr-48.png",
    "128": "icons/titlr-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "index.js"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "<all_urls>"
  ]
}