Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Allow constructing spdy executor from existing transports
If you already have an existing transport, it is not always possible to reconstruct a client config from it.
Allow constructing a spdy executor, given a connection/upgrade transport
```release-note
NONE
```
294f28f25d