Destroy SkScanlineDecoder in the SkCodec subclass destructors

src/codec/SkJpegCodec.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 SkJpegCodec_DEFINED
 #define SkJpegCodec_DEFINED
 
@@ skipping 77 matching lines @@
      * Called only by NewFromStream
      *
      * @param srcInfo contains the source width and height
      * @param stream the encoded image data
      * @param decoderMgr holds decompress struct, src manager, and error manager
      *                   takes ownership
      */
     SkJpegCodec(const SkImageInfo& srcInfo, SkStream* stream, JpegDecoderMgr* decoderMgr);
 
     /*
+     * Explicit destructor is used to ensure that the scanline decoder is deleted
+     * before the decode manager.
+     */
+    ~SkJpegCodec() override;
+
+    /*
      * Handles rewinding the input stream if it is necessary
      */
     bool handleRewind();
 
     /*
      * Checks if we can scale to the requested dimensions and scales the dimensions
      * if possible
      */
     bool scaleToDimensions(uint32_t width, uint32_t height);
 
     /*
      * Create the swizzler based on the encoded format
      */
     void initializeSwizzler(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
             const Options& options);
 
     SkAutoTDelete<JpegDecoderMgr> fDecoderMgr;
     SkAutoTDelete<SkSwizzler>     fSwizzler;
     size_t                        fSrcRowBytes;
 
     friend class SkJpegScanlineDecoder;
 
     typedef SkCodec INHERITED;
 };
 
 #endif