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/tests/GrSurfaceTest.cpp b/tests/GrSurfaceTest.cpp
index 18c0275..a7c688d 100644
--- a/tests/GrSurfaceTest.cpp
+++ b/tests/GrSurfaceTest.cpp
@@ -65,7 +65,7 @@
     REPORTER_ASSERT(reporter, static_cast<GrSurface*>(texRT2->asRenderTarget()) ==
                     static_cast<GrSurface*>(texRT2->asTexture()));
 
-    gpu->deleteTestingOnlyBackendTexture(&backendTex);
+    gpu->deleteTestingOnlyBackendTexture(backendTex);
 }
 
 // This test checks that the isConfigTexturable and isConfigRenderable are