Examine source code of Custom selection

{
  "manifest_version": 2,
  "name": "__MSG_appName__",
  "author": "Pythack",
  "default_locale": "en",
  "version": "2.1.0",
  "description": "__MSG_appDesc__",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "<all_urls>",
    "storage",
    "tabs",
    "activeTab"
  ],
  "browser_action": {
    "default_icon": {
      "16": "images/icon-16.png",
      "48": "images/icon-48.png",
      "128": "images/icon.png"
    },
    "default_title": "__MSG_appName__",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "images/icon-16.png",
    "48": "images/icon-48.png",
    "128": "images/icon.png"
  },
  "web_accessible_resources": [
    "images/icon.png",
    "images/iconcustom.png",
    "images/iconvalid.png",
    "images/iconfail.png",
    "images/icondisabled.png"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{bfdbd07f-d146-49cb-8a0d-9a133aa33e75}"
    }
  }
}