Make GrXferProcessor and related classes private.

Change-Id: I81ea6f5ea5c8b7b23848ef24524a7e48e531efe8
Reviewed-on: https://skia-review.googlesource.com/8819
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/gn/gpu.gni b/gn/gpu.gni
index db3ebc6..11ac1cf 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -39,13 +39,9 @@
   "$_include/gpu/GrTestUtils.h",
   "$_include/gpu/GrTypes.h",
   "$_include/gpu/GrTypesPriv.h",
-  "$_include/gpu/GrXferProcessor.h",
 
   "$_include/gpu/effects/GrBlurredEdgeFragmentProcessor.h",
   "$_include/gpu/effects/GrConstColorProcessor.h",
-  "$_include/gpu/effects/GrCoverageSetOpXP.h",
-  "$_include/gpu/effects/GrCustomXfermode.h",
-  "$_include/gpu/effects/GrPorterDuffXferProcessor.h",
   "$_include/gpu/effects/GrXfermodeFragmentProcessor.h",
 
   "$_include/gpu/gl/GrGLAssembleInterface.h",
@@ -225,6 +221,7 @@
   "$_src/gpu/GrWindowRectangles.h",
   "$_src/gpu/GrWindowRectsState.h",
   "$_src/gpu/GrXferProcessor.cpp",
+  "$_src/gpu/GrXferProcessor.h",
   "$_src/gpu/GrYUVProvider.cpp",
   "$_src/gpu/GrYUVProvider.h",
 
@@ -302,7 +299,9 @@
   "$_src/gpu/effects/GrConfigConversionEffect.h",
   "$_src/gpu/effects/GrConstColorProcessor.cpp",
   "$_src/gpu/effects/GrCoverageSetOpXP.cpp",
+  "$_src/gpu/effects/GrCoverageSetOpXP.h",
   "$_src/gpu/effects/GrCustomXfermode.cpp",
+  "$_src/gpu/effects/GrCustomXfermode.h",
   "$_src/gpu/effects/GrBezierEffect.cpp",
   "$_src/gpu/effects/GrBezierEffect.h",
   "$_src/gpu/effects/GrConvexPolyEffect.cpp",
@@ -324,6 +323,7 @@
   "$_src/gpu/effects/GrOvalEffect.cpp",
   "$_src/gpu/effects/GrOvalEffect.h",
   "$_src/gpu/effects/GrPorterDuffXferProcessor.cpp",
+  "$_src/gpu/effects/GrPorterDuffXferProcessor.h",
   "$_src/gpu/effects/GrProxyMove.h",
   "$_src/gpu/effects/GrRRectEffect.cpp",
   "$_src/gpu/effects/GrRRectEffect.h",