GrFP can express distance vector field req., program builder declares variable for it

gyp/core.gypi

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # Include this gypi to include all 'core' files
 # The parent gyp/gypi file must define
 #       'skia_src_path'     e.g. skia/trunk/src
 #       'skia_include_path' e.g. skia/trunk/include
 #
 # The skia build defines these in common_variables.gypi
@@ skipping 179 matching lines @@
         '<(skia_src_path)/core/SkNinePatchIter.cpp',
         '<(skia_src_path)/core/SkNinePatchIter.h',
         '<(skia_src_path)/core/SkNormalBevelSource.cpp',
         '<(skia_src_path)/core/SkNormalBevelSource.h',
         '<(skia_src_path)/core/SkNormalMapSource.cpp',
         '<(skia_src_path)/core/SkNormalMapSource.h',
         '<(skia_src_path)/core/SkNormalFlatSource.cpp',
         '<(skia_src_path)/core/SkNormalFlatSource.h',
         '<(skia_src_path)/core/SkNormalSource.cpp',
         '<(skia_src_path)/core/SkNormalSource.h',
+        '<(skia_src_path)/core/SkNormalSourcePriv.h',
         '<(skia_src_path)/core/SkNx.h',
         '<(skia_src_path)/core/SkOpts.cpp',
         '<(skia_src_path)/core/SkOpts.h',
         '<(skia_src_path)/core/SkOrderedReadBuffer.h',
         '<(skia_src_path)/core/SkPaint.cpp',
         '<(skia_src_path)/core/SkPaintDefaults.h',
         '<(skia_src_path)/core/SkPaintPriv.cpp',
         '<(skia_src_path)/core/SkPaintPriv.h',
         '<(skia_src_path)/core/SkPath.cpp',
         '<(skia_src_path)/core/SkPathEffect.cpp',
@@ skipping 294 matching lines @@
         '<(skia_src_path)/pathops/SkPathOpsLine.h',
         '<(skia_src_path)/pathops/SkPathOpsPoint.h',
         '<(skia_src_path)/pathops/SkPathOpsQuad.h',
         '<(skia_src_path)/pathops/SkPathOpsRect.h',
         '<(skia_src_path)/pathops/SkPathOpsTSect.h',
         '<(skia_src_path)/pathops/SkPathOpsTypes.h',
         '<(skia_src_path)/pathops/SkPathWriter.h',
         '<(skia_src_path)/pathops/SkReduceOrder.h',
     ],
 }