Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageRef_ashmem.h

Index: src/images/SkImageRef_ashmem.h
diff --git a/src/images/SkImageRef_ashmem.h b/src/images/SkImageRef_ashmem.h
index f98507aabcf73799a241e7420fdc95f534ecc612..efee5e759b95ad9bd75483ba94beac4f1fcdec1b 100644
--- a/src/images/SkImageRef_ashmem.h
+++ b/src/images/SkImageRef_ashmem.h
@@ -19,7 +19,7 @@ struct SkAshmemRec {
 
 class SkImageRef_ashmem : public SkImageRef {
 public:
-    SkImageRef_ashmem(SkStream*, SkBitmap::Config, int sampleSize = 1);
+    SkImageRef_ashmem(SkStreamRewindable*, SkBitmap::Config, int sampleSize = 1);
     virtual ~SkImageRef_ashmem();
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkImageRef_ashmem)
@@ -28,7 +28,7 @@ protected:
     SkImageRef_ashmem(SkFlattenableReadBuffer&);
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
 
-    virtual bool onDecode(SkImageDecoder* codec, SkStream* stream,
+    virtual bool onDecode(SkImageDecoder* codec, SkStreamRewindable* stream,
                           SkBitmap* bitmap, SkBitmap::Config config,
                           SkImageDecoder::Mode mode);