Move GrVkInterface out of public API.

Bug: skia:
Change-Id: I8b73982e4c9372af1c35bfc5e665c2c146d7d9f5
Reviewed-on: https://skia-review.googlesource.com/141121
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/gn/gpu.gni b/gn/gpu.gni
index f4877a5..45aafa5 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -536,7 +536,6 @@
 skia_vk_sources = [
   "$_include/gpu/vk/GrVkBackendContext.h",
   "$_include/gpu/vk/GrVkDefines.h",
-  "$_include/gpu/vk/GrVkInterface.h",
   "$_include/gpu/vk/GrVkMemoryAllocator.h",
   "$_include/gpu/vk/GrVkTypes.h",
   "$_include/private/GrVkTypesPriv.h",
@@ -576,6 +575,7 @@
   "$_src/gpu/vk/GrVkIndexBuffer.cpp",
   "$_src/gpu/vk/GrVkIndexBuffer.h",
   "$_src/gpu/vk/GrVkInterface.cpp",
+  "$_src/gpu/vk/GrVkInterface.h",
   "$_src/gpu/vk/GrVkMemory.cpp",
   "$_src/gpu/vk/GrVkMemory.h",
   "$_src/gpu/vk/GrVkPipeline.cpp",