Examine source code of Plurk: Paste images

{
  "name": "__MSG_appName__",
  "version": "0.1.2resigned1",
  "manifest_version": 2,
  "description": "__MSG_appDescription__",
  "icons": {
    "16": "images/icon-16.png",
    "128": "images/icon-128.png"
  },
  "default_locale": "en",
  "permissions": [
    "tabs",
    "http://plurk.com/*",
    "https://plurk.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.plurk.com/*",
        "*://plurk.com/*"
      ],
      "js": [
        "scripts/contentscript.js"
      ],
      "run_at": "document_end",
      "all_frames": false
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5b777a40-3b5f-49f2-b69a-6b6414a30c19}"
    }
  }
}