Examine source code of Basecamp 3 Me Button

{
  "description": "Adds Me button back to menu for Basecamp 3.",
  "manifest_version": 2,
  "name": "Basecamp 3 Me Button",
  "version": "1.2resigned1",
  "homepage_url": "https://about.me/wilsonglasser",
  "icons": {
    "48": "icons/48.png"
  },
  "applications": {
    "gecko": {
      "id": "basecamp3mebutton@wilsonglasser.com",
      "strict_min_version": "45.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://3.basecamp.com/*"
      ],
      "js": [
        "mebutton.js"
      ]
    }
  ]
}