Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageDecoder_libwebp.cpp

 /*
  * Copyright 2010, The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
@@ skipping 92 matching lines @@
     }
     virtual ~SkWEBPImageDecoder() {
         SkSafeUnref(fInputStream);
     }
 
     virtual Format getFormat() const SK_OVERRIDE {
         return kWEBP_Format;
     }
 
 protected:
-    virtual bool onBuildTileIndex(SkStream *stream, int *width, int *height) SK_OVERRIDE;
+    virtual bool onBuildTileIndex(SkStreamRewindable *stream, int *width, int *height) SK_OVERRIDE;
     virtual bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) SK_OVERRIDE;
     virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
 
 private:
     /**
      *  Called when determining the output config to request to webp.
      *  If the image does not have alpha, there is no need to premultiply.
      *  If the caller wants unpremultiplied colors, that is respected.
      */
     bool shouldPremultiply() const {
@@ skipping 169 matching lines @@
         return false;
     }
 
     decodedBitmap->setConfig(config, width, height, 0);
 
     decodedBitmap->setIsOpaque(!fHasAlpha);
 
     return true;
 }
 
-bool SkWEBPImageDecoder::onBuildTileIndex(SkStream* stream,
+bool SkWEBPImageDecoder::onBuildTileIndex(SkStreamRewindable* stream,
                                           int *width, int *height) {
     int origWidth, origHeight, hasAlpha;
     if (!webp_parse_header(stream, &origWidth, &origHeight, &hasAlpha)) {
         return false;
     }
 
     if (!stream->rewind()) {
         SkDebugf("Failed to rewind webp stream!");
         return false;
     }
@@ skipping 254 matching lines @@
 
     return ok;
 }
 
 
 ///////////////////////////////////////////////////////////////////////////////
 DEFINE_DECODER_CREATOR(WEBPImageDecoder);
 DEFINE_ENCODER_CREATOR(WEBPImageEncoder);
 ///////////////////////////////////////////////////////////////////////////////
 
-static SkImageDecoder* sk_libwebp_dfactory(SkStream* stream) {
+static SkImageDecoder* sk_libwebp_dfactory(SkStreamRewindable* stream) {
     int width, height, hasAlpha;
     if (!webp_parse_header(stream, &width, &height, &hasAlpha)) {
         return NULL;
     }
 
     // Magic matches, call decoder
     return SkNEW(SkWEBPImageDecoder);
 }
 
-static SkImageDecoder::Format get_format_webp(SkStream* stream) {
+static SkImageDecoder::Format get_format_webp(SkStreamRewindable* stream) {
     int width, height, hasAlpha;
     if (webp_parse_header(stream, &width, &height, &hasAlpha)) {
         return SkImageDecoder::kWEBP_Format;
     }
     return SkImageDecoder::kUnknown_Format;
 }
 
 static SkImageEncoder* sk_libwebp_efactory(SkImageEncoder::Type t) {
       return (SkImageEncoder::kWEBP_Type == t) ? SkNEW(SkWEBPImageEncoder) : NULL;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libwebp_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_webp);
 static SkImageEncoder_EncodeReg gEReg(sk_libwebp_efactory);