Make GrGpu::deleteTestingOnlyBackendTexture() take const GrBackendTexture&

Change-Id: Ibd00d0dc6d8c73628f26851e102defdbafab149b
Reviewed-on: https://skia-review.googlesource.com/113164
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/vk/GrVkGpu.h b/src/gpu/vk/GrVkGpu.h
index 81517af..b5ddcb8 100644
--- a/src/gpu/vk/GrVkGpu.h
+++ b/src/gpu/vk/GrVkGpu.h
@@ -75,7 +75,7 @@
                                                      bool isRenderTarget,
                                                      GrMipMapped) override;
     bool isTestingOnlyBackendTexture(const GrBackendTexture&) const override;
-    void deleteTestingOnlyBackendTexture(GrBackendTexture*) override;
+    void deleteTestingOnlyBackendTexture(const GrBackendTexture&) override;
 
     GrBackendRenderTarget createTestingOnlyBackendRenderTarget(int w, int h, GrColorType,
                                                                GrSRGBEncoded) override;