Can mirroring be used to upgrade SSRS? Can you use mirroring to upgrade SSRS? 

For instance, I've upgraded from SQL 2005 to SQL 2014 with mirroring. 

SSRS is running on the same box as my database server.  I'm going from SQL 2012 (11.0.5343) to 2014 SP1.

I was hoping to get info from the community to upgrade in the easiest way with any possible caveats.
Assuming native mode here...

The main thing you are migrating when doing the upgrade to SQL Server 2014 is the reports, subscriptions, and then your data connections. I can't think of a reason why you would need to put this database in replication just for an upgrade. Also, while it probably could be done (and work) it is not a supported method of upgrade from Microsoft to put the SSRS databases in mirroring configuration. So proceed at your own risk.

Unless you are adding/modifying reports or subscriptions often I would not see why you could not just do a quick migration according to documentation. Perform your testing of the new version with your reports, and then at cut-over time just do a backup/restore one last time.