Remove ownership aruments from render target wrap functions

We never adopt render targets (just borrow them).

BUG=skia:

Change-Id: Ie899b814a7a81339a8735bbd7ad9facc66e580d7
Reviewed-on: https://skia-review.googlesource.com/9525
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/tools/gpu/GrTest.cpp b/tools/gpu/GrTest.cpp
index 15faffa..28c1738 100644
--- a/tools/gpu/GrTest.cpp
+++ b/tools/gpu/GrTest.cpp
@@ -340,8 +340,7 @@
         return nullptr;
     }
 
-    sk_sp<GrRenderTarget> onWrapBackendRenderTarget(const GrBackendRenderTargetDesc&,
-                                                    GrWrapOwnership) override {
+    sk_sp<GrRenderTarget> onWrapBackendRenderTarget(const GrBackendRenderTargetDesc&) override {
         return nullptr;
     }