The Tor Browser / file revision

 Additional IP Rights Grant (Patents)

 "This implementation" means the copyrightable works distributed by

 Google as part of the WebM Project.

 Google hereby grants to you a perpetual, worldwide, non-exclusive,

 no-charge, royalty-free, irrevocable (except as stated in this section)

 patent license to make, have made, use, offer to sell, sell, import,

 transfer, and otherwise run, modify and propagate the contents of this

 implementation of VP8, where such license applies only to those patent

 claims, both currently owned by Google and acquired in the future,

 licensable by Google that are necessarily infringed by this

 implementation of VP8. This grant does not include claims that would be

 infringed only as a consequence of further modification of this

 implementation. If you or your agent or exclusive licensee institute or

 order or agree to the institution of patent litigation against any

 entity (including a cross-claim or counterclaim in a lawsuit) alleging

 that this implementation of VP8 or any code incorporated within this

 implementation of VP8 constitutes direct or contributory patent

 infringement, or inducement of patent infringement, then any patent

 rights granted to you under this License for this implementation of VP8

 shall terminate as of the date such litigation is filed.