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.
 
-typedef SkTRegistry<SkImageDecoder*, SkStream*> DecodeReg;
+typedef SkTRegistry<SkImageDecoder*, SkStreamRewindable*> DecodeReg;
 
 // N.B. You can't use "DecodeReg::gHead here" due to complex C++
 // corner cases.
-template DecodeReg* SkTRegistry<SkImageDecoder*, SkStream*>::gHead;
+template DecodeReg* SkTRegistry<SkImageDecoder*, SkStreamRewindable*>::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 DecodeReg* curr = 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;
 }
 
-typedef SkTRegistry<SkImageDecoder::Format, SkStream*> FormatReg;
+typedef SkTRegistry<SkImageDecoder::Format, SkStreamRewindable*> FormatReg;
 
-template FormatReg* SkTRegistry<SkImageDecoder::Format, SkStream*>::gHead;
+template FormatReg* SkTRegistry<SkImageDecoder::Format, SkStreamRewindable*>::gHead;
 
-SkImageDecoder::Format SkImageDecoder::GetStreamFormat(SkStream* stream) {
+SkImageDecoder::Format SkImageDecoder::GetStreamFormat(SkStreamRewindable* stream) {
     const FormatReg* curr = 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;
 }