Examine source code of Yahoo! Mail Alerter

{
  "manifest_version": 2,
  "name": "Yahoo! Mail Alerter",
  "version": "1.5.3",
  "browser_specific_settings": {
    "gecko": {
      "id": "yma@ngokimphu",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "description": "Alert you when new emails arrived in your Yahoo! Mail box",
  "icons": {
    "48": "icons/yma-48.png"
  },
  "browser_action": {
    "default_icon": "icons/yma-48.png"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.mail.yahoo.com/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "storage",
    "notifications",
    "contextMenus",
    "https://mail.yahoo.com/",
    "https://login.yahoo.com/"
  ]
}