Reland of Add guards to GrTextureProvider

src/gpu/GrDrawContext.cpp

Index: src/gpu/GrDrawContext.cpp
diff --git a/src/gpu/GrDrawContext.cpp b/src/gpu/GrDrawContext.cpp
index 01bd161b3010080f694098e5f1a2d77d73cd0e30..497af7ce9b764fa0b64c21b2759db1e68e1753c7 100644
--- a/src/gpu/GrDrawContext.cpp
+++ b/src/gpu/GrDrawContext.cpp
@@ -57,7 +57,10 @@
     , fDrawTarget(SkSafeRef(rt->getLastDrawTarget()))
     , fTextContext(nullptr)
     , fSurfaceProps(SkSurfacePropsCopyOrDefault(surfaceProps))
-    , fSingleOwner(singleOwner) {
+#ifdef SK_DEBUG
+    , fSingleOwner(singleOwner)
+#endif
+{
     SkDEBUGCODE(this->validate();)
 }