Examine source code of popup url

{
  "description": "Quick popup. Select a text, and then pop up a window in current page not a new tab immediately, with content based on your selection and configured url.",
  "manifest_version": 2,
  "name": "popup url",
  "version": "0.4",
  "homepage_url": "https://github.com/derekchuank/popup-extension",
  "icons": {
    "48": "icons/popup.png"
  },
  "applications": {
    "gecko": {
      "id": "example@test.com"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script/popup.js"
      ]
    }
  ],
  "permissions": [
    "<all_urls>",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/popup.png",
    "default_title": "popup url",
    "default_popup": "toobar/toobar.html",
    "browser_style": true
  }
}