Show Google Spreadsheet comments

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Show Google Spreadsheet comments",
  "version": "0.4.2",
  "manifest_version": 2,
  "description": "Show button to show comments in google spreadsheet",
  "homepage_url": "https://doro.space",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_title": "Show comments"
  },
  "permissions": [
    "https://docs.google.com/spreadsheets/*"
  ]
}