Store ninepatch chunks in the png header in CodexTest

src/codec/SkCodec_libpng.cpp

 /*
  * 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 "SkCodec_libpng.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 241 matching lines @@
 
     // FIXME: Could we use the return value of setjmp to specify the type of
     // error?
     if (setjmp(png_jmpbuf(png_ptr))) {
         return false;
     }
 
     png_set_read_fn(png_ptr, static_cast<void*>(stream), sk_read_fn);
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
-    // FIXME: Does this need to be installed so early?
-    // hookup our chunkReader so we can see any user-chunks the caller may be interested in
+    // Hookup our chunkReader so we can see any user-chunks the caller may be interested in.
+    // This needs to be installed before we read the png header.  Android may store ninepatch
+    // chunks in the header.
     if (chunkReader) {
         png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, (png_byte*)"", 0);
         png_set_read_user_chunk_fn(png_ptr, (png_voidp) chunkReader, sk_read_user_chunk);
     }
 #endif
 
     // The call to png_read_info() gives us all of the information from the
     // PNG file before the first IDAT (image data chunk).
     png_read_info(png_ptr, info_ptr);
     png_uint_32 origWidth, origHeight;
@@ skipping 584 matching lines @@
     }
 
     if (1 == numberPasses) {
         return new SkPngScanlineDecoder(imageInfo, streamDeleter.detach(), chunkReader,
                                         png_ptr, info_ptr, bitDepth);
     }
 
     return new SkPngInterlacedScanlineDecoder(imageInfo, streamDeleter.detach(), chunkReader,
                                               png_ptr, info_ptr, bitDepth, numberPasses);
 }