Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageDecoder_FactoryRegistrar.cpp

 /*
  * Copyright 2013 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 "SkErrorInternals.h"
 #include "SkImageDecoder.h"
 #include "SkStream.h"
 #include "SkTRegistry.h"
 
 // This file is used for registration of SkImageDecoders. It also holds a function
 // for checking all the the registered SkImageDecoders for one that matches an
-// input SkStream.
+// input SkStreamRewindable.
 
 template SkImageDecoder_DecodeReg* SkImageDecoder_DecodeReg::gHead;
 
-SkImageDecoder* image_decoder_from_stream(SkStream*);
+SkImageDecoder* image_decoder_from_stream(SkStreamRewindable*);
 
-SkImageDecoder* image_decoder_from_stream(SkStream* stream) {
+SkImageDecoder* image_decoder_from_stream(SkStreamRewindable* stream) {
     SkImageDecoder* codec = NULL;
     const SkImageDecoder_DecodeReg* curr = SkImageDecoder_DecodeReg::Head();
     while (curr) {
         codec = curr->factory()(stream);
         // we rewind here, because we promise later when we call "decode", that
         // the stream will be at its beginning.
         bool rewindSuceeded = stream->rewind();
 
         // our image decoder's require that rewind is supported so we fail early
         // if we are given a stream that does not support rewinding.
         if (!rewindSuceeded) {
             SkDEBUGF(("Unable to rewind the image stream."));
             SkDELETE(codec);
             return NULL;
         }
 
         if (codec) {
             return codec;
         }
         curr = curr->next();
     }
     return NULL;
 }
 
 template SkImageDecoder_FormatReg* SkImageDecoder_FormatReg::gHead;
 
-SkImageDecoder::Format SkImageDecoder::GetStreamFormat(SkStream* stream) {
+SkImageDecoder::Format SkImageDecoder::GetStreamFormat(SkStreamRewindable* stream) {
     const SkImageDecoder_FormatReg* curr = SkImageDecoder_FormatReg::Head();
     while (curr != NULL) {
         Format format = curr->factory()(stream);
         if (!stream->rewind()) {
             SkErrorInternals::SetError(kInvalidOperation_SkError,
                                        "Unable to rewind the image stream\n");
             return kUnknown_Format;
         }
         if (format != kUnknown_Format) {
             return format;
         }
         curr = curr->next();
     }
     return kUnknown_Format;
 }