Have gpu createTestingOlyBackendTexture know if it is a render target or not

src/gpu/vk/GrVkGpu.h

Index: src/gpu/vk/GrVkGpu.h
diff --git a/src/gpu/vk/GrVkGpu.h b/src/gpu/vk/GrVkGpu.h
index a9470aee14c19847f3bcd7ad797105668ad65643..011189aaddce231d84f5cf5f53113ce390f97d5f 100644
--- a/src/gpu/vk/GrVkGpu.h
+++ b/src/gpu/vk/GrVkGpu.h
@@ -80,7 +80,8 @@ public:
     void xferBarrier(GrRenderTarget*, GrXferBarrierType) override {}
 
     GrBackendObject createTestingOnlyBackendTexture(void* pixels, int w, int h,
-                                                    GrPixelConfig config) override;
+                                                    GrPixelConfig config,
+                                                    bool isRenderTarget) override;
     bool isTestingOnlyBackendTexture(GrBackendObject id) const override;
     void deleteTestingOnlyBackendTexture(GrBackendObject id, bool abandonTexture) override;