Examine source code of RainbowFromPaint

{
  "theme": {
    "images": {
      "theme_frame": "persona_rainbow_head.png"
    },
    "colors": {
      "frame": "#8a11ed",
      "tab_background_text": "#de0707"
    }
  },
  "version": "2.0",
  "name": "RainbowFromPaint",
  "manifest_version": 2,
  "description": "This is a cool rainbow thingy"
}