Handle SkStream::rewind properly.

src/images/SkImageRef.cpp

Index: src/images/SkImageRef.cpp
diff --git a/src/images/SkImageRef.cpp b/src/images/SkImageRef.cpp
index 299166c31ccc4a50c3a6402535c45abcab5ef44f..8785ab3854a7684f73a2e98309f02872837f430d 100644
--- a/src/images/SkImageRef.cpp
+++ b/src/images/SkImageRef.cpp
@@ -107,7 +107,10 @@ bool SkImageRef::prepareBitmap(SkImageDecoder::Mode mode) {
 
     SkASSERT(fBitmap.getPixels() == NULL);
 
-    fStream->rewind();
+    if (!fStream->rewind()) {
+        SkDEBUGF(("Failed to rewind SkImageRef stream!"));
+        return false;
+    }
 
     SkImageDecoder* codec;
     if (fFactory) {
@@ -184,6 +187,15 @@ void SkImageRef::flatten(SkFlattenableWriteBuffer& buffer) const {
     buffer.writeUInt(fConfig);
     buffer.writeInt(fSampleSize);
     buffer.writeBool(fDoDither);
-    fStream->rewind();
-    buffer.writeStream(fStream, fStream->getLength());
+    // FIXME: It seems this logic should go into writeStream itself.
+    // Not that we have any other streams to write, but if we ever
+    // do...
+    if (!fStream->rewind()) {
+        SkDEBUGF(("Failed to rewind SkImageRef stream!"));
+        buffer.write32(0);
+    } else {
+        // And we need to handle this call to getLength properly as well.
+        // FIXME: Perhaps this class should take an SkStreamAsset
+        buffer.writeStream(fStream, fStream->getLength());
+    }
 }