Examine source code of Symptom Tracker

{
  "manifest_version": 2,
  "name": "Symptom Tracker",
  "version": "1.0",
  "description": "Record and track your daily symptoms.",
  "permissions": [],
  "browser_action": {
    "default_popup": "index.html",
    "default_icon": {
      "128": "images/sym-logo.png"
    }
  },
  "icons": {
    "128": "images/sym-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e77c2928-4bb5-46e9-845b-7e65d4864962}"
    }
  }
}