Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageDecoder_libgif.cpp

Index: src/images/SkImageDecoder_libgif.cpp
diff --git a/src/images/SkImageDecoder_libgif.cpp b/src/images/SkImageDecoder_libgif.cpp
index d368eccd92d629537ae7b8cedf68b1dc29d81970..a15307280e04babc8b877b978d8bac7bfef0d8d2 100644
--- a/src/images/SkImageDecoder_libgif.cpp
+++ b/src/images/SkImageDecoder_libgif.cpp
@@ -23,7 +23,7 @@ public:
     }
 
 protected:
-    virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode mode) SK_OVERRIDE;
+    virtual bool onDecode(SkStreamRewindable* stream, SkBitmap* bm, Mode mode) SK_OVERRIDE;
 
 private:
     typedef SkImageDecoder INHERITED;
@@ -93,7 +93,7 @@ private:
 
 static int DecodeCallBackProc(GifFileType* fileType, GifByteType* out,
                               int size) {
-    SkStream* stream = (SkStream*) fileType->UserData;
+    SkStreamRewindable* stream = (SkStreamRewindable*) fileType->UserData;
     return (int) stream->read(out, size);
 }
 
@@ -154,7 +154,7 @@ static bool error_return(GifFileType* gif, const SkBitmap& bm,
     return false;
 }
 
-bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) {
+bool SkGIFImageDecoder::onDecode(SkStreamRewindable* sk_stream, SkBitmap* bm, Mode mode) {
 #if GIFLIB_MAJOR < 5
     GifFileType* gif = DGifOpen(sk_stream, DecodeCallBackProc);
 #else
@@ -356,7 +356,7 @@ DONE:
 DEFINE_DECODER_CREATOR(GIFImageDecoder);
 ///////////////////////////////////////////////////////////////////////////////
 
-static bool is_gif(SkStream* stream) {
+static bool is_gif(SkStreamRewindable* stream) {
     char buf[GIF_STAMP_LEN];
     if (stream->read(buf, GIF_STAMP_LEN) == GIF_STAMP_LEN) {
         if (memcmp(GIF_STAMP,   buf, GIF_STAMP_LEN) == 0 ||
@@ -370,20 +370,20 @@ static bool is_gif(SkStream* stream) {
 
 #include "SkTRegistry.h"
 
-static SkImageDecoder* sk_libgif_dfactory(SkStream* stream) {
+static SkImageDecoder* sk_libgif_dfactory(SkStreamRewindable* stream) {
     if (is_gif(stream)) {
         return SkNEW(SkGIFImageDecoder);
     }
     return NULL;
 }
 
-static SkTRegistry<SkImageDecoder*, SkStream*> gReg(sk_libgif_dfactory);
+static SkTRegistry<SkImageDecoder*, SkStreamRewindable*> gReg(sk_libgif_dfactory);
 
-static SkImageDecoder::Format get_format_gif(SkStream* stream) {
+static SkImageDecoder::Format get_format_gif(SkStreamRewindable* stream) {
     if (is_gif(stream)) {
         return SkImageDecoder::kGIF_Format;
     }
     return SkImageDecoder::kUnknown_Format;
 }
 
-static SkTRegistry<SkImageDecoder::Format, SkStream*> gFormatReg(get_format_gif);
+static SkTRegistry<SkImageDecoder::Format, SkStreamRewindable*> gFormatReg(get_format_gif);