Examine source code of Yank It!

{
  "manifest_version": 2,
  "name": "Yank It!",
  "version": "1.1",
  "description": "Changes middle-mouse autoscrolling to a mobile-like dragging gesture.",
  "icons": {
    "48": "icons/icon.png",
    "96": "icons/icon@2x.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "yank-it.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "icons/icon.svg",
    "default_title": "Yank It!",
    "default_popup": "config/index.htm"
  },
  "options_ui": {
    "page": "config/index.htm"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "yank-it@nullspeak.github.io"
    }
  }
}