Add GrDebugMarkerOp

Change-Id: I948838dea13d2f36194ca1043ab37e72759794e0
Reviewed-on: https://skia-review.googlesource.com/31740
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/gn/gpu.gni b/gn/gpu.gni
index e9b33ed..6cea1d6 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -248,6 +248,7 @@
   "$_src/gpu/ops/GrDefaultPathRenderer.cpp",
   "$_src/gpu/ops/GrDefaultPathRenderer.h",
   "$_src/gpu/ops/GrDiscardOp.h",
+  "$_src/gpu/ops/GrDebugMarkerOp.h",
   "$_src/gpu/ops/GrDrawAtlasOp.cpp",
   "$_src/gpu/ops/GrDrawAtlasOp.h",
   "$_src/gpu/ops/GrDrawOp.h",