Revert "Revert "Change how vertex/instance attributes are handled in geometry processors.""

This reverts commit 5045e501d2aec23e5f1e4b46346033ac3202c6b0.

TBR=csmartdalton@google.com

Change-Id: Ifbf5f1d8f8ef340fdc69653e931b6d68d4bf0854
Reviewed-on: https://skia-review.googlesource.com/135862
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/gm/convexpolyeffect.cpp b/gm/convexpolyeffect.cpp
index 18c5ebd..496b6b1 100644
--- a/gm/convexpolyeffect.cpp
+++ b/gm/convexpolyeffect.cpp
@@ -83,10 +83,9 @@
         sk_sp<GrGeometryProcessor> gp(GrDefaultGeoProcFactory::Make(
                 color, Coverage::kSolid_Type, LocalCoords::kUnused_Type, SkMatrix::I()));
 
-        size_t vertexStride = gp->getVertexStride();
-        SkASSERT(vertexStride == sizeof(SkPoint));
+        SkASSERT(gp->debugOnly_vertexStride() == sizeof(SkPoint));
         QuadHelper helper;
-        SkPoint* verts = reinterpret_cast<SkPoint*>(helper.init(target, vertexStride, 1));
+        SkPoint* verts = reinterpret_cast<SkPoint*>(helper.init(target, sizeof(SkPoint), 1));
         if (!verts) {
             return;
         }