Consolidate SkCodec functions for handling rewind

src/codec/SkCodec_wbmp.h

Index: src/codec/SkCodec_wbmp.h
diff --git a/src/codec/SkCodec_wbmp.h b/src/codec/SkCodec_wbmp.h
index cec398d34b8e036a9574b4d09d6d046fa278be20..8c5466105cfecfab422f9ab843acc8030cba50ee 100644
--- a/src/codec/SkCodec_wbmp.h
+++ b/src/codec/SkCodec_wbmp.h
@@ -33,13 +33,8 @@ protected:
     SkEncodedFormat onGetEncodedFormat() const override;
     Result onGetPixels(const SkImageInfo&, void*, size_t,
                        const Options&, SkPMColor[], int*) override;
+    bool onRewind() override;
 private:
-
-    /*
-     * Calls rewindIfNeeded and returns true if the decoder can continue
-     */
-    bool handleRewind();
-
     /*
      * Returns a swizzler on success, NULL on failure
      */