Measuring deletion of cookies included in browsers used by online system users

A method comprising:

• receiving a request to connect to an online system from a client device associated with a user of a plurality of users of the online system;
• retrieving user identifying information associated with the user;
• retrieving a cookie from the client device from which the request to connect to the online system was received, the client device associated with the user of the online system;
• determining a condition is satisfied based on the retrieved cookie and the retrieved user identifying information, wherein determining the condition is satisfied comprises:
• determining a time associated with the received request to connect to the online system;
• determining a time when the user most recently connected to the online system based on the retrieved information stored in a browser on the client device by the online system;
• and determining that a difference between the time associated with the received request and the time when the user most recently connected to the online system exceeds a threshold value;
• or
• determining a user identifier associated with a prior connection to the online system from the retrieved information stored in a browser on the client device by the online system;
• and determining if the user identifier associated with the prior connection to the online system matches the retrieved user identifying information associated with the user by the online system;
• modifying the retrieved user identifying information stored by the online system in the browser on the client device based at least in part on the received request to connect to the online system;
• and
• responsive to the determined condition being satisfied, sending to the client device the retrieved user identifying information associated with the user and a plurality of redirect instructions, wherein the plurality of redirect instructions cause the browser on the client device to communicate information stored in the browser by a third party system and the retrieved user identifying information to the third party system.

A computer program product comprising a non-transitory computer readable storage medium having instructions encoded therein that, when executed by a processor cause the processor to:

• retrieve user identifying information associated with a user of a plurality of users of an online system;
• retrieve a cookie from a client device from which a request to connect to the online system was received, the client device associated with the user of the online system;
• determine a condition is satisfied based on the retrieved cookie and the retrieved user identifying information, determining the condition comprises:
• determining user identifying information associated with a prior connection to the online system from the client device based on the retrieved cookie;
• and
• determining if the user identifying information associated with the prior connection to the online system matches the user identifying information associated with the user;
• or
• determining a time associated with receiving a request to connect to the online system;
• determining a time when the user most recently connected to the online system based on the retrieved cookie;
• and
• determining that a difference between the time associated with the received request and the time when the user most recently connected to the online system exceeds a threshold value;
• and
• responsive to the determined condition being satisfied, send to the client device the retrieved user identifying information associated with the user and a plurality of redirect instructions, wherein the plurality of redirect instructions cause a browser on the client device to communicate information stored in the browser by a third party system and the retrieved user identifying information to the third party system.