add -Iinclude/private anywhere we have -Isrc/core

gyp/pdf.gyp

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # This file builds the PDF backend.
 {
   'targets': [
     {
       'target_name': 'pdf',
       'product_name': 'skia_pdf',
       'type': 'static_library',
       'standalone_static_library': 1,
       'variables': { 'skia_pdf_use_sfntly%': 1, },
       'dependencies': [
         'skia_lib.gyp:skia_lib',
         'skflate.gyp:skflate',
       ],
       'includes': [
         'pdf.gypi',
       ],
       'include_dirs': [
+        '../include/private',
         '../src/core', # needed to get SkGlyphCache.h and SkTextFormatParams.h
         '../src/pdf',
         '../src/utils', # needed to get SkBitSet.h
       ],
       'sources': [
         'pdf.gypi', # Makes the gypi appear in IDEs (but does not modify the build).
       ],
       'conditions': [
         [ 'skia_pdf_use_sfntly and not skia_android_framework and \
            skia_os in ["win", "android", "linux", "chromeos", "mac"]',
@@ skipping 18 matching lines @@
         'defines': [
           'SK_SUPPORT_PDF',
         ],
         'include_dirs': [
           '../include/core',  # SkDocument.h
         ],
       },
     },
   ],
 }