Option for SkCodec to treat dst as all zeroes.

src/codec/SkCodec.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.h"
 #include "SkData.h"
 #include "SkCodec_libpng.h"
@@ skipping 21 matching lines @@
     if (!data) {
         return NULL;
     }
     return NewFromStream(SkNEW_ARGS(SkMemoryStream, (data)));
 }
 
 SkCodec::SkCodec(const SkImageInfo& info, SkStream* stream)
     : fInfo(info)
     , fStream(stream)
     , fNeedsRewind(false)
+    , fZeroInitialized(kNo_ZeroInitialized)
 {}
 
 bool SkCodec::rewindIfNeeded() {
     // Store the value of fNeedsRewind so we can update it. Next read will
     // require a rewind.
     const bool neededRewind = fNeedsRewind;
     fNeedsRewind = true;
     return !neededRewind || fStream->rewind();
 }