Enable Notifications

[timqian]

The extension only shows unread count on the badge.

People might also want to get a notification for unread content.

It can be helpful to add an option for users to receive notifications of unread content.

[Possible way to implement]

• add a notification toggle in src/options.html and save the toggle to localstorge
• in src/utils/queries.js when querying GET_USER_UNREAD, query not only summaries but also contents.
• in src/background.jscheck unread contents and notify user if necessary
  1. query unread contents
  2. check if user turned on notifications, if turned on, send user notifications and save notification time(used to decide if a notification is already sent in the next check)

Ref

• sample code to send notifications: b002e8c