Examine source code of Link Drop

{
  "name": "Link Drop",
  "description": "Get reminded of important links when it's convenient",
  "version": "1.0.4",
  "permissions": [
    "storage",
    "activeTab",
    "https://www.linkdrop.co/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9dbdcfe2-0318-4b96-80e3-0a0d1e55504c}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Save your current page",
    "default_icon": {
      "16": "default_icon_inactive_16.png",
      "32": "default_icon_inactive_32.png",
      "48": "default_icon_inactive_48.png",
      "128": "default_icon_inactive.png"
    }
  },
  "icons": {
    "16": "default_icon_16.png",
    "32": "default_icon_32.png",
    "48": "default_icon_48.png",
    "128": "default_icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.linkdrop.co/*"
      ],
      "js": [
        "sync_script.js"
      ]
    }
  ],
  "manifest_version": 2
}