Add wrapBackendTextureAsRenderTarget API

src/gpu/GrTest.cpp

Index: src/gpu/GrTest.cpp
diff --git a/src/gpu/GrTest.cpp b/src/gpu/GrTest.cpp
index 04122e13198a35119cf1fd4c1a14e21a3352ea96..77016a7f2d1971bbc3746fd034c03ee96052d564 100644
--- a/src/gpu/GrTest.cpp
+++ b/src/gpu/GrTest.cpp
@@ -339,6 +339,11 @@ private:
         return nullptr;
     }
 
+    GrRenderTarget* onWrapBackendTextureAsRenderTarget(const GrBackendTextureDesc&,
+                                                       GrWrapOwnership) override {
+        return nullptr;
+    }
+
     GrVertexBuffer* onCreateVertexBuffer(size_t size, bool dynamic) override { return nullptr; }
 
     GrIndexBuffer* onCreateIndexBuffer(size_t size, bool dynamic) override { return nullptr; }