Gmail" Notifier (Dev Edition) per InBasic

This is a rewrite of my "Gmail Notifier (restartless)" extension. The idea is to have a flexible email notifier to get notified on any user-requested query. Same as the original extension, this one does not need credentials to work. It relies on the logged-in accounts.

Features:
1. Notifies of incoming emails from any user-defined query
2. Supports all common actions: Mark as read, report spam, archive, delete right from the popup view
3. Lists all emails that match the current query on the popup view
4. Supports desktop notification and customized sound alerts
5. Supports viewing emails with provided content-security policy to prevent the loading of any remote resources.
6. Supports customization of the tooltip notification

This extension is compatible with Gmail API and hence with email delegation. It is possible to assign one or multiple accounts to use this interface to communicate with Gmail. Also, the extension optionally supports native messaging to be able to communicate with the "notmuch" email client. both of these features are still disabled for this release.

Notes:
This is still an experimental extension. Please report bugs or request new features either on the FAQs page or the GitHub page.

Privacy:
This extension only communicates with Gmail to show unread emails or to perform an action like mark an email as read. There are no other server-side activities.