Examine source code of DiffSpotter

{
  "manifest_version": 2,
  "name": "DiffSpotter",
  "version": "1.0",
  "description": "Highlight differences in content and layout between web pages",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "<all_urls>",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "DiffSpotter",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1431b236-2061-4e6c-a875-14ab0e6ef9af}"
    }
  }
}