Remove SkImage_Base::peekProxy.

This is the only place we provide a proxy from a SkImage other than
asView() and is only used in one place in the library. Add a utility
function to replace uses in tests based on asView().

Bug: skia:11208
Change-Id: Ica6eae6e5f153f208523331566acc0360925a20e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/373617
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
21 files changed