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

src/gpu/gl/GrGLGpu.h

Index: src/gpu/gl/GrGLGpu.h
diff --git a/src/gpu/gl/GrGLGpu.h b/src/gpu/gl/GrGLGpu.h
index aead715d1efc8907cbb8c3fc9c185e3ae208b4bd..4df2de066f6ef80f1f79717dcb12bcf5c35e0167 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -133,7 +133,8 @@ public:
                                                                 int height) override;
 
     GrBackendObject createTestingOnlyBackendTexture(void* pixels, int w, int h,
-                                                    GrPixelConfig config) override;
+                                                    GrPixelConfig config,
+                                                    bool isRenderTarget = false) override;
     bool isTestingOnlyBackendTexture(GrBackendObject) const override;
     void deleteTestingOnlyBackendTexture(GrBackendObject, bool abandonTexture) override;