Examine source code of RainbowNote

{
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "RainbowNote@Sungho.Hwang",
      "strict_min_version": "88.0"
    }
  },
  "name": "RainbowNote",
  "version": "31.1",
  "description": "Notes with rainbow colors.",
  "icons": {
    "32": "rn32.png"
  },
  "browser_action": {
    "default_icon": "rn32.png",
    "default_title": "RainbowNote"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "storage",
    "tabs",
    "activeTab"
  ]
}