Handle rewinds in SkBmpCodec.

src/codec/SkCodec_libbmp.h

Index: src/codec/SkCodec_libbmp.h
diff --git a/src/codec/SkCodec_libbmp.h b/src/codec/SkCodec_libbmp.h
index 3328af26a02e65ad8d1aeaf8fc955f0e50f85e52..650259ad16cea6b8191097c6a80455768458defd 100644
--- a/src/codec/SkCodec_libbmp.h
+++ b/src/codec/SkCodec_libbmp.h
@@ -100,6 +100,15 @@ private:
 
     /*
      *
+     * Read enough of the stream to initialize the SkBmpCodec. Returns a bool
+     * representing success or failure. If it returned true, and codecOut was
+     * not NULL, it will be set to a new SkBmpCodec.
+     *
+     */
+    static bool ReadHeader(SkStream*, bool isIco, SkCodec** codecOut);
+
+    /*
+     *
      * Performs the bitmap decoding for bit masks input format
      *
      */