Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkMovie_gif.cpp

Index: src/images/SkMovie_gif.cpp
diff --git a/src/images/SkMovie_gif.cpp b/src/images/SkMovie_gif.cpp
index e4c70037de54bb234f9a398e7f7b0a3a5c45f961..b6d068a391c64d7e9e9dc3905f04cfc6558df753 100644
--- a/src/images/SkMovie_gif.cpp
+++ b/src/images/SkMovie_gif.cpp
@@ -432,7 +432,7 @@ bool SkGIFMovie::onGetBitmap(SkBitmap* bm)
 
 #include "SkTRegistry.h"
 
-SkMovie* Factory(SkStream* stream) {
+SkMovie* Factory(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 ||
@@ -446,4 +446,4 @@ SkMovie* Factory(SkStream* stream) {
     return NULL;
 }
 
-static SkTRegistry<SkMovie*(*)(SkStream*)> gReg(Factory);
+static SkTRegistry<SkMovie*(*)(SkStreamRewindable*)> gReg(Factory);