Examine source code of HighlightHunter

{
  "manifest_version": 2,
  "name": "HighlightHunter",
  "version": "1.1",
  "description": "Highlights words on double-click and toggles via toolbar icon.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "HighlightHunter"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "author": "Roman Slezak",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "all_frames": true
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c1d29057-ecce-4db9-a97a-838de9dbb519}"
    }
  }
}