Providing notifications on online social networks

1. A method comprising:

by a server computing device associated with a social-networking system, receiving a registration request from an application running on a client system, wherein the registration request comprises a messaging token provided by a message-distribution server and one or more cookies associated with the social-networking system;

by the server computing device, registering, in response to the received registration request, the messaging token to a user profile on the social-networking system, wherein registering the messaging token to the user profile further comprises identifying the user profile based on the one or more cookies, the one or more cookies indicating that the user associated with the user profile was, at a time the registration request was received by the server computing device, logged into the social-networking system on the application;

by the server computing device, generating a push notification for display at the client system;

by the server computing device, sending the push notification to the client system via the message-distribution server, wherein the sending comprises sending, to the message-distribution server, the push notification generated by the server computing device and the messaging token received from the application running on the client system and provided by the message-distribution server, and wherein the messaging token identifies the client system to the message-distribution server for delivery of the push notification.

2. The method of claim 1 , wherein the registration request comprises a request to receive push notifications from the server computing device associated with the social-networking system at the application.

3. The method of claim 1 , wherein the application is a web browser.

4. The method of claim 3 , wherein the push notification comprises an interactive feature, and wherein the interactive feature comprises instructions to cause the web browser to open a particular web page associated with the push notification.

5. The method of claim 1 , wherein the push notification is sent to the message-distribution server as part of a message, wherein the push notification is included in an encrypted payload of the message, and wherein the token is included in a header of the message.

6. The method of claim 1 , wherein the token comprises an authorization key for the social-networking system to access message-distribution services of the message-distribution server.

7. The method of claim 1 , wherein the token identifies, to the message-distribution server, the client system and the application for delivery of the push notification.

8. The method of claim 1 , wherein the message-distribution server is associated with the social-networking system.

9. The method of claim 1 , wherein the push notification comprises instructions to cause the application to determine whether the application has permission to provide the push notification before displaying the push notification to the user of the client system.

10. The method of claim 9 , wherein the determining whether the application has permission comprises determining whether the user is currently logged in to the social-networking system on the application.

11. One or more computer-readable non-transitory storage media associated with a server computing device associated with a social-networking system embodying software that is operable when executed to:

receive a registration request from an application running on a client system, wherein the registration request comprises a messaging token provided by a message-distribution server and one or more cookies associated with the social-networking system;

register, in response to the received registration request, the messaging token to a user profile on the social-networking system, wherein registering the messaging token to the user profile further comprises identifying the user profile based on the one or more cookies, the one or more cookies indicating that the user associated with the user profile was, at a time the registration request was received by the server computing device, logged into the social-networking system on the application;

generate a push notification for display at the client system;

send the push notification to the client system via the message-distribution server, wherein the sending comprises sending, to the message-distribution server, the push notification generated by the server computing device and the messaging token received from the application running on the client system and provided by the message-distribution server, and wherein the messaging token identifies the client system to the message-distribution server for delivery of the push notification.

12. The media of claim 11 , wherein the registration request comprises a request to receive push notifications from the server computing device associated with the social-networking system at the application.

13. The media of claim 11 , wherein the application is a web browser.

14. A server system associated with a social-networking system, comprising: one or more processors; and a memory coupled to the processors comprising instructions executable by the processors, the processors operable when executing the instructions to:

receive a registration request from an application running on a client system, wherein the registration request comprises a messaging token provided by a message-distribution server and one or more cookies associated with the social-networking system;

register, in response to the received registration request, the messaging token to a user profile on the social-networking system, wherein registering the messaging token to the user profile further comprises identifying the user profile based on the one or more cookies, the one or more cookies indicating that the user associated with the user profile was, at a time the registration request was received by the server computing device, logged into the social-networking system on the application;

generate a push notification for display at the client system;

send the push notification to the client system via the message-distribution server, wherein the sending comprises sending, to the message-distribution server, the push notification generated by the server computing device and the messaging token received from the application running on the client system and provided by the message-distribution server, and wherein the messaging token identifies the client system to the message-distribution server for delivery of the push notification.

15. The system of claim 14 , wherein the registration request comprises a request to receive push notifications from the server computing device associated with the social-networking system at the application.

16. The system of claim 14 , wherein the application is a web browser.

17. The system of claim 16 , wherein the push notification comprises an interactive feature, and wherein the interactive feature comprises instructions to cause the web browser to open a particular web page associated with the push notification.