Fix Debian9-Clang build

TBR=bsalomon@google.com
Change-Id: I2e86aa0381d409f1205bdaba4117253cb381b404
Reviewed-on: https://skia-review.googlesource.com/65020
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/tests/Test.h b/tests/Test.h
index 7ef2932..3e34474 100644
--- a/tests/Test.h
+++ b/tests/Test.h
@@ -22,7 +22,7 @@
 class GLTestContext;
 }  // namespace sk_gpu_test
 class GrContext;
-class GrContextOptions;
+struct GrContextOptions;
 #endif
 
 namespace skiatest {