Examine source code of TwitchTime

{
  "manifest_version": 2,
  "name": "TwitchTime",
  "version": "1.10",
  "browser_specific_settings": {
    "gecko": {
      "id": "twitchtime@notactuallytwitch.com",
      "strict_min_version": "55.0"
    }
  },
  "description": "Keeps track of how long you have watched different Twitch channels.",
  "homepage_url": "https://github.com/swpease/TwitchTime",
  "icons": {
    "48": "icons/twitch-time-48.png",
    "96": "icons/twitch-time-48@2x.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitch.tv/*"
      ],
      "js": [
        "content_scripts/content_script.js"
      ],
      "css": [
        "content_scripts/content_script.css"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/twitch-time-16-light.png",
      "32": "icons/twitch-time-32-light.png",
      "64": "icons/twitch-time-64-light.png"
    },
    "default_title": "Twitch Time",
    "default_popup": "popup/popup.html",
    "browser_style": true
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "permissions": [
    "storage"
  ]
}