Consolidate SkCodec functions for handling rewind

src/codec/SkCodec_wbmp.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCodec_wbmp_DEFINED
 #define SkCodec_wbmp_DEFINED
 
@@ skipping 15 matching lines @@
     /*
      * Assumes IsWbmp was called and returned true
      * Creates a wbmp scanline decoder
      * Takes ownership of the stream
      */
     static SkScanlineDecoder* NewSDFromStream(SkStream*);
 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
      */
     SkSwizzler* initializeSwizzler(const SkImageInfo& info, const SkPMColor* ctable,
                                    const Options& opts);
 
     /*
      * Read a src row from the encoded stream
      */
     Result readRow(uint8_t* row);
 
     SkWbmpCodec(const SkImageInfo&, SkStream*);
 
     const size_t fSrcRowBytes;
 
     friend class SkWbmpScanlineDecoder;
     typedef SkCodec INHERITED;
 };
 
 #endif  // SkCodec_wbmp_DEFINED