Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageDecoder_libbmp.cpp

Index: src/images/SkImageDecoder_libbmp.cpp
diff --git a/src/images/SkImageDecoder_libbmp.cpp b/src/images/SkImageDecoder_libbmp.cpp
index 2edd57c0d17fa0dc4edd624be58151a67d90c311..3eb181f781bc9d699d83a4c656003e3895fac700 100644
--- a/src/images/SkImageDecoder_libbmp.cpp
+++ b/src/images/SkImageDecoder_libbmp.cpp
@@ -34,7 +34,7 @@ private:
 DEFINE_DECODER_CREATOR(BMPImageDecoder);
 ///////////////////////////////////////////////////////////////////////////////
 
-static bool is_bmp(SkStream* stream) {
+static bool is_bmp(SkStreamRewindable* stream) {
     static const char kBmpMagic[] = { 'B', 'M' };
 
 
@@ -44,7 +44,7 @@ static bool is_bmp(SkStream* stream) {
         !memcmp(buffer, kBmpMagic, sizeof(kBmpMagic));
 }
 
-static SkImageDecoder* sk_libbmp_dfactory(SkStream* stream) {
+static SkImageDecoder* sk_libbmp_dfactory(SkStreamRewindable* stream) {
     if (is_bmp(stream)) {
         return SkNEW(SkBMPImageDecoder);
     }
@@ -53,7 +53,7 @@ static SkImageDecoder* sk_libbmp_dfactory(SkStream* stream) {
 
 static SkImageDecoder_DecodeReg gReg(sk_libbmp_dfactory);
 
-static SkImageDecoder::Format get_format_bmp(SkStream* stream) {
+static SkImageDecoder::Format get_format_bmp(SkStreamRewindable* stream) {
     if (is_bmp(stream)) {
         return SkImageDecoder::kBMP_Format;
     }