Auto Boomerang by Siege Media

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Auto Boomerang by Siege Media",
  "description": "Adds a button to the compose window in Gmail that will automatically Boomerang messages based on your chosen settings",
  "version": "1.1",
  "manifest_version": 2,
  "icons": {
    "16": "images/icon.png",
    "48": "images/icon.png",
    "128": "images/icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "css": [
        "css/styles.css"
      ],
      "js": [
        "vendor/jquery-2.0.0.min.js",
        "vendor/jquery.storageapi.min.js",
        "vendor/mutation_summary.js",
        "vendor/moment.min.js",
        "lib/auto-followup-extension.js"
      ]
    }
  ]
}