Ser or Estar - That is the question

manifest.json

{
  "update_url": "http://clients2.google.com/service/update2/crx",
  "name": "Ser or Estar - That is the question",
  "manifest_version": 2,
  "version": "0.2.1",
  "description": "Highlights every form of the Spanish verbs 'ser' or 'estar'.",
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "permissions": [
    "http://*/",
    "https://*/",
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "main.js"
    ],
    "persistent": false
  },
  "options_page": "options.html",
  "browser_action": {
    "default_icon": {
      "19": "images/icon19.png",
      "38": "images/icon38.png"
    },
    "default_title": "Ser or Estar"
  }
}