Make SkStream *not* ref counted.

include/images/SkDecodingImageGenerator.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkDecodingImageGenerator_DEFINED
 #define SkDecodingImageGenerator_DEFINED
 
@@ skipping 67 matching lines @@
         const bool        fRequireUnpremul;
     };
 
     /**
      *  These two functions return a SkImageGenerator that calls into
      *  SkImageDecoder.  They return NULL on failure.
      *
      *  The SkData version of this function is preferred.  If the stream
      *  has an underlying SkData (such as a SkMemoryStream) pass that in.
      *
-     *  This object will unref the stream when done or on failure.  Since
-     *  streams have internal state (position), the caller should not pass
-     *  a shared stream in.  Pass either a new duplicated stream in or
-     *  transfer ownership of the stream.  This factory asserts
-     *  stream->unique().
-     *
-     *  For example:
-     *    SkStreamRewindable* stream;
-     *    ...
-     *    SkImageGenerator* gen
-     *        = SkDecodingImageGenerator::Create(
-     *            stream->duplicate(), SkDecodingImageGenerator::Options());
-     *    ...
-     *    SkDELETE(gen);
+     *  This object, if non-NULL, takes ownership of stream and deletes stream
+     *  upon deletion. If NULL is returned, stream is deleted immediately.
      *
      *  @param Options (see above)
      *
      *  @return NULL on failure, a new SkImageGenerator on success.
      */
     SkImageGenerator* Create(SkStreamRewindable* stream,
                              const Options& opt);
 
     /**
      *  @param data Contains the encoded image data that will be used by
@@ skipping 10 matching lines @@
 //         SkDecodingImageGenerator::Create(
 //             data, SkDecodingImageGenerator::Options()), dst, NULL);
 //  }
 //  bool install_stream(SkStreamRewindable* stream, SkBitmap* dst) {
 //     return SkInstallDiscardablePixelRef(
 //         SkDecodingImageGenerator::Create(
 //             stream, SkDecodingImageGenerator::Options()), dst, NULL);
 //  }
 
 #endif  // SkDecodingImageGenerator_DEFINED