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

TBR=bsalomon@google.com
Change-Id: Ifcfe56b1117b64821b2bfc34ba36d120227d15fa
Reviewed-on: https://skia-review.googlesource.com/25802
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/tests/ReadWriteAlphaTest.cpp b/tests/ReadWriteAlphaTest.cpp
index 344400c..2e5a1dc 100644
--- a/tests/ReadWriteAlphaTest.cpp
+++ b/tests/ReadWriteAlphaTest.cpp
@@ -50,6 +50,7 @@
     {
         GrSurfaceDesc desc;
         desc.fFlags     = kNone_GrSurfaceFlags;
+        desc.fOrigin    = kTopLeft_GrSurfaceOrigin;
         desc.fConfig    = kAlpha_8_GrPixelConfig;    // it is a single channel texture
         desc.fWidth     = X_SIZE;
         desc.fHeight    = Y_SIZE;
@@ -153,6 +154,7 @@
         for (int rt = 0; rt < 2; ++rt) {
             GrSurfaceDesc desc;
             desc.fFlags     = rt ? kRenderTarget_GrSurfaceFlag : kNone_GrSurfaceFlags;
+            desc.fOrigin    = rt ? kBottomLeft_GrSurfaceOrigin : kTopLeft_GrSurfaceOrigin;
             desc.fConfig    = config;
             desc.fWidth     = X_SIZE;
             desc.fHeight    = Y_SIZE;