Examine source code of Pomodoro Blocker

{
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "57.0"
    }
  },
  "name": "Pomodoro Blocker",
  "version": "0.5.1",
  "description": "Pomodoro timer that blocks distraction away",
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "pomodoro.png",
    "default_popup": "popup/small_win.html"
  },
  "permissions": [
    "notifications",
    "storage",
    "webRequest",
    "webRequestBlocking",
    "http://*/",
    "https://*/"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "back.html",
    "popup/small_win.html"
  ]
}