created GrMtlPipelineStateDataManager for metal gpu backend

Bug: skia:
Change-Id: I630b1fc2e3a4195b8df8b04a02be8fc95bb9c4fe
Reviewed-on: https://skia-review.googlesource.com/145329
Commit-Queue: Timothy Liang <timliang@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/gn/gpu.gni b/gn/gpu.gni
index 7178147..4139c4c 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -639,6 +639,8 @@
   "$_src/gpu/mtl/GrMtlPipelineState.mm",
   "$_src/gpu/mtl/GrMtlPipelineStateBuilder.h",
   "$_src/gpu/mtl/GrMtlPipelineStateBuilder.mm",
+  "$_src/gpu/mtl/GrMtlPipelineStateDataManager.h",
+  "$_src/gpu/mtl/GrMtlPipelineStateDataManager.mm",
   "$_src/gpu/mtl/GrMtlRenderTarget.h",
   "$_src/gpu/mtl/GrMtlRenderTarget.mm",
   "$_src/gpu/mtl/GrMtlResourceProvider.h",