Examine source code of Roamhelper

{
  "manifest_version": 2,
  "name": "Roamhelper",
  "version": "1.0",
  "description": "Unofficial Roam extension",
  "icons": {
    "32": "icons/favicon-32x32.png",
    "128": "icons/android-chrome-128x128.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/favicon-32x32.png",
    "default_title": "Roamhelper",
    "default_popup": "popup/popup.html"
  }
}