Check in pnglibconf.h so we don't need to generate it.

gyp/libpng.gyp

 # Copyright 2014 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'skia_warnings_as_errors': 0,
   },
   'targets': [
     {
       'target_name': 'libpng',
       'conditions': [
         [ 'skia_libpng_static',
           {
             'type': 'static_library',
             'include_dirs': [
               '../third_party/externals/libpng',
+              # Needed for generated pnglibconf.h
+              '../third_party/libpng',
             ],
             'dependencies': [
               'zlib.gyp:zlib',
             ],
             'export_dependent_settings': [
               'zlib.gyp:zlib',
             ],
             'direct_dependent_settings': {
               'include_dirs': [
                 '../third_party/externals/libpng',
+                # Needed for generated pnglibconf.h
+                '../third_party/libpng',
               ],
             },
             'cflags': [
               '-w',
               '-fvisibility=hidden',
             ],
             'conditions': [
               ['not arm_neon', {
                 'defines': [
                     # FIXME: Why is this needed? Without it, pngpriv.h sets it
                     # to 2 if __ARM_NEON is defined, but shouldn't __ARM_NEON
                     # not be defined since arm_neon is 0?
                     'PNG_ARM_NEON_OPT=0',
                 ],
               }],
             ],
-            'actions': [
-              {
-                'action_name': 'generate_pngconf',
-                'variables' : {
-                  'prebuilt': '../third_party/externals/libpng/scripts/pnglibconf.h.prebuilt',
-                  'generated': '../third_party/externals/libpng/pnglibconf.h',
-                },
-                'inputs': [
-                  '<(prebuilt)',
-                ],
-                'outputs': [
-                  '<(generated)',
-                ],
-                'action': ['python', 'copy_file.py', '<(prebuilt)', '<(generated)'],
-              },
-            ],
             'sources': [
               '../third_party/externals/libpng/png.c',
               '../third_party/externals/libpng/pngerror.c',
               '../third_party/externals/libpng/pngget.c',
               '../third_party/externals/libpng/pngmem.c',
               '../third_party/externals/libpng/pngpread.c',
               '../third_party/externals/libpng/pngread.c',
               '../third_party/externals/libpng/pngrio.c',
               '../third_party/externals/libpng/pngrtran.c',
               '../third_party/externals/libpng/pngrutil.c',
@@ skipping 32 matching lines @@
                   },
                 }
               ]
             ]
           }
         ]
       ],
     },
   ]
 }