Fifth small fragment from "Reduce dependence on GrSurface's origin field"

TBR=bsalomon@google.com
Change-Id: Id59fa3d2cd657e84f1b4db32847bc07e850271f4
Reviewed-on: https://skia-review.googlesource.com/26362
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrTextureAdjuster.cpp b/src/gpu/GrTextureAdjuster.cpp
index be29857..11cb5b3 100644
--- a/src/gpu/GrTextureAdjuster.cpp
+++ b/src/gpu/GrTextureAdjuster.cpp
@@ -58,6 +58,7 @@
     sk_sp<GrTextureProxy> copy = CopyOnGpu(fContext, std::move(proxy), contentArea, copyParams);
     if (copy) {
         if (key.isValid()) {
+            SkASSERT(copy->origin() == this->originalProxy()->origin());
             fContext->resourceProvider()->assignUniqueKeyToProxy(key, copy.get());
             this->didCacheCopy(key);
         }