Totally block trying to flush a ddl drawmgr

This should never be possible.

Bug: skia:10877
Change-Id: I476ece42182b2296da528a2b3a3a2587c5bfedea
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/332719
Auto-Submit: Adlai Holler <adlai@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
1 file changed