Rename 'dstView' to 'outputView' to avoid confusion w/ 'dstProxyView'

This is just a simple clean up from a CL request.

Change-Id: Ibc09e19aeb8a160e4e4e03573fcf56cb1d58525b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/273983
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
11 files changed