Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageDecoder_wbmp.cpp

Index: src/images/SkImageDecoder_wbmp.cpp
diff --git a/src/images/SkImageDecoder_wbmp.cpp b/src/images/SkImageDecoder_wbmp.cpp
index 9460d558994c06b8fad181837479863ea4dd8a22..4a9944dbcda30f85fe743518484346870f292ecf 100644
--- a/src/images/SkImageDecoder_wbmp.cpp
+++ b/src/images/SkImageDecoder_wbmp.cpp
@@ -152,7 +152,7 @@ bool SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap,
 DEFINE_DECODER_CREATOR(WBMPImageDecoder);
 ///////////////////////////////////////////////////////////////////////////////
 
-static SkImageDecoder* sk_wbmp_dfactory(SkStream* stream) {
+static SkImageDecoder* sk_wbmp_dfactory(SkStreamRewindable* stream) {
     wbmp_head   head;
 
     if (head.init(stream)) {
@@ -161,7 +161,7 @@ static SkImageDecoder* sk_wbmp_dfactory(SkStream* stream) {
     return NULL;
 }
 
-static SkImageDecoder::Format get_format_wbmp(SkStream* stream) {
+static SkImageDecoder::Format get_format_wbmp(SkStreamRewindable* stream) {
     wbmp_head head;
     if (head.init(stream)) {
         return SkImageDecoder::kWBMP_Format;