Examine source code of AddHeader

{
  "description": "add header",
  "manifest_version": 2,
  "name": "AddHeader",
  "version": "1.2resigned1",
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icons/header-48.png"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser_action": {
    "default_title": "Add Headers",
    "default_icon": "icons/header-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{95644318-7d69-4074-bec9-59fae034270b}"
    }
  }
}