1. A method implemented in a computing device, the method comprising: receiving, by a notification system of the computing device and from multiple applications, both metadata for multiple notifications associated with the multiple applications and content for the multiple notifications, the notification system not being a same application as each of the multiple applications, the metadata having an indication of when to present content for respective notifications of the multiple applications; ceasing execution of the multiple applications; maintaining, by the notification system, the multiple notifications; in response to transitioning to settings of the computing device in which notifications would be observable at the computing device and for one or more of the multiple applications: determining, by the notification system, at least one of the multiple notifications for presentation; and updating, by the notification system of the computing device, without resuming execution of the application associated with the determined notification, without input from a user of the computing device, and at a time based at least in part on an indication included in the metadata of when to present content of the determined notification, a representation of the application associated with the determined notification in a user interface (UI) to present the content for the determined notification within the representation of the application, the UI containing a plurality of representations of the multiple applications presented by the notification system, the representation of the application being one of the plurality of representations of the multiple applications contained in the UI, the presentation of the content within the representation of the application enabling the user of the computing device to consume the content: through the representation of the application associated with the determined notification; without executing or resuming execution of the application associated with the determined notification; and without requiring input from the user of the computing device to the UI or the representation of the application associated with the determined notification.