Destroy SkScanlineDecoder in the SkCodec subclass destructors

include/codec/SkCodec.h

Index: include/codec/SkCodec.h
diff --git a/include/codec/SkCodec.h b/include/codec/SkCodec.h
index 2e47a261f3924f2b018d988af56440f4310de2d3..96bd2c0b88b16c3386f1b1843d2f82db2abc2e2f 100644
--- a/include/codec/SkCodec.h
+++ b/include/codec/SkCodec.h
@@ -168,15 +168,23 @@ protected:
      */
     RewindState SK_WARN_UNUSED_RESULT rewindIfNeeded();
 
-    /*
-     *
+    /**
      * Get method for the input stream
-     *
      */
     SkStream* stream() {
         return fStream.get();
     }
 
+    /**
+     * If the codec has a scanline decoder, return it (no ownership change occurs)
+     * else return NULL.
+     * The returned decoder is valid while the codec exists and the client has not
+     * created a new scanline decoder.
+     */
+    SkScanlineDecoder* scanlineDecoder() {
+        return fScanlineDecoder.get();
+    }
+
 private:
     SkAutoTDelete<SkStream>             fStream;
     bool                                fNeedsRewind;