Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageRef_GlobalPool.cpp

Index: src/images/SkImageRef_GlobalPool.cpp
diff --git a/src/images/SkImageRef_GlobalPool.cpp b/src/images/SkImageRef_GlobalPool.cpp
index 6af8653217765d32a9048a09260502f61b1c772e..352dd42d9f79a3c94dabafff20edbeeb7fdb8b99 100644
--- a/src/images/SkImageRef_GlobalPool.cpp
+++ b/src/images/SkImageRef_GlobalPool.cpp
@@ -24,7 +24,7 @@ static SkImageRefPool* GetGlobalPool() {
     return gPool;
 }
 
-SkImageRef_GlobalPool::SkImageRef_GlobalPool(SkStream* stream,
+SkImageRef_GlobalPool::SkImageRef_GlobalPool(SkStreamRewindable* stream,
                                              SkBitmap::Config config,
                                              int sampleSize)
         : SkImageRef(stream, config, sampleSize, &gGlobalPoolMutex) {
@@ -44,7 +44,7 @@ SkImageRef_GlobalPool::~SkImageRef_GlobalPool() {
  *  that we also are already inside the mutex. Hence, we can reference
  *  the global-pool directly.
  */
-bool SkImageRef_GlobalPool::onDecode(SkImageDecoder* codec, SkStream* stream,
+bool SkImageRef_GlobalPool::onDecode(SkImageDecoder* codec, SkStreamRewindable* stream,
                                      SkBitmap* bitmap, SkBitmap::Config config,
                                      SkImageDecoder::Mode mode) {
     if (!this->INHERITED::onDecode(codec, stream, bitmap, config, mode)) {