Examine source code of Ecsta

{
  "manifest_version": 2,
  "name": "Ecsta",
  "short_name": "Ecsta",
  "version": "1.1.0",
  "description": "A simple new tab extension meant to stay out of your way while still making for great eye-candy.",
  "icons": {
    "32": "./res/icons/32.png",
    "48": "./res/icons/48.png",
    "64": "./res/icons/64.png",
    "128": "./res/icons/128.png",
    "256": "./res/icons/256.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "Ecsta@kckarnige.github.io"
    }
  },
  "chrome_settings_overrides": {
    "homepage": "./index.html"
  },
  "chrome_url_overrides": {
    "newtab": "./index.html"
  }
}