Remove SK_ENABLE_LIBPNG define as it is no longer needed by Android.

src/images/SkImageDecoder_libpng.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkImageDecoder.h"
@@ skipping 1068 matching lines @@
     return true;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 DEFINE_DECODER_CREATOR(PNGImageDecoder);
 DEFINE_ENCODER_CREATOR(PNGImageEncoder);
 ///////////////////////////////////////////////////////////////////////////////
 
 #include "SkTRegistry.h"
 
-#ifdef SK_ENABLE_LIBPNG
-    SkImageDecoder* sk_libpng_dfactory(SkStream*);
-    SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type);
-#endif
-
 SkImageDecoder* sk_libpng_dfactory(SkStream* stream) {
     char buf[PNG_BYTES_TO_CHECK];
     if (stream->read(buf, PNG_BYTES_TO_CHECK) == PNG_BYTES_TO_CHECK &&
         !png_sig_cmp((png_bytep) buf, (png_size_t)0, PNG_BYTES_TO_CHECK)) {
         return SkNEW(SkPNGImageDecoder);
     }
     return NULL;
 }
 
 SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kPNG_Type == t) ? SkNEW(SkPNGImageEncoder) : NULL;
 }
 
 static SkTRegistry<SkImageEncoder*, SkImageEncoder::Type> gEReg(sk_libpng_efactory);
 static SkTRegistry<SkImageDecoder*, SkStream*> gDReg(sk_libpng_dfactory);