Add SkCodec, including PNG implementation.

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',
             ],
             'dependencies': [
               'zlib.gyp:zlib',
             ],
-            'export_dependent_settings': [
-              'zlib.gyp:zlib',
-            ],
             'direct_dependent_settings': {
               'include_dirs': [
                 '../third_party/externals/libpng',
               ],
             },
             'cflags': [
               '-w',
               '-fvisibility=hidden',
             ],
+            '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/pnggccrd.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',
               '../third_party/externals/libpng/pngset.c',
               '../third_party/externals/libpng/pngtrans.c',
-              '../third_party/externals/libpng/pngvcrd.c',
               '../third_party/externals/libpng/pngwio.c',
               '../third_party/externals/libpng/pngwrite.c',
               '../third_party/externals/libpng/pngwtran.c',
               '../third_party/externals/libpng/pngwutil.c',
             ],
           }, {  # not skia_libpng_static
             'type': 'none',
-            'conditions': [
-              [ 'skia_os == "android"',
-                {
-                  # TODO(halcanary): merge all png targets into this file.
-                  'dependencies': [
-                    'android_deps.gyp:png',
-                  ],
-                  'export_dependent_settings': [
-                    'android_deps.gyp:png',
-                  ],
-                }, {  # skia_os != "android"
-                  'dependencies': [
-                    'zlib.gyp:zlib',
-                    ],
-                  'export_dependent_settings': [
-                    'zlib.gyp:zlib',
-                    ],
-                  'direct_dependent_settings': {
-                    'link_settings': {
-                      'libraries': [
-                        '-lpng',
-                      ],
-                    },
-                  },
-                }
-              ]
-            ]
+            'dependencies': [
+              'zlib.gyp:zlib',
+            ],
+            'export_dependent_settings': [
+              'zlib.gyp:zlib',
+            ],
+            'direct_dependent_settings': {
+              'link_settings': {
+                'libraries': [
+                    '-lpng',
+                ],
+              },
+            },
           }
         ]
       ],
     },
   ]
 }