Examine source code of Pruuf

{
  "manifest_version": 2,
  "name": "Pruuf",
  "description": "This extension shows spelling and grammar proofing results for Malay, English and Chinese language.",
  "version": "1.35",
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "applications": {
    "gecko": {
      "id": "pruuf@getpruuf.com"
    }
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Check your language with Pruuf"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*",
        "file:///*"
      ],
      "js": [
        "content.js"
      ],
      "all_frames": true,
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "activeTab",
    "http://*/",
    "https://*/"
  ]
}