Examine source code of Circle Tweet Detector

{
  "manifest_version": 2,
  "name": "Circle Tweet Detector",
  "version": "1.0.0.1",
  "description": "Runs a simple script on Twitter webpages and adds a left and right green border to circle tweets in your timeline.",
  "icons": {
    "48": "icons/Circle-Tweet-Detector-48.png",
    "96": "icons/Circle-Tweet-Detector-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://twitter.com/*"
      ],
      "js": [
        "circleDetector.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{52ec84ff-2afa-49d6-8ea4-b7c69c868c52}"
    }
  }
}