Handle zero-length encoded images gracefully during deserialization

include/core/SkPicture.h

 /*
  * Copyright 2007 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPicture_DEFINED
 #define SkPicture_DEFINED
 
@@ skipping 85 matching lines @@
     /** Return a cull rect for this picture.
         Ops recorded into this picture that attempt to draw outside the cull might not be drawn.
      */
     virtual SkRect cullRect() const = 0;
 
     /** Returns a non-zero value unique among all pictures. */
     uint32_t uniqueID() const;
 
     /**
      *  Serialize to a stream. If non NULL, serializer will be used to serialize
-     *  any bitmaps in the picture.
-     *
-     *  TODO: Use serializer to serialize SkImages as well.
+     *  bitmaps and images in the picture.

[scroggo, 2015/09/04 18:48:20]

I like that we turn bitmaps into images! I was thinking though, that if we ever
captured an SKP that was created with bitmaps, we might get difference
performance numbers in our tests due to converting to images. Maybe that's okay
though, especially since we are switching to image anyway.

      */
     void serialize(SkWStream*, SkPixelSerializer* = NULL) const;
 
     /**
      *  Serialize to a buffer.
      */
     void flatten(SkWriteBuffer&) const;
 
     /**
      * Returns true if any bitmaps may be produced when this SkPicture
@@ skipping 78 matching lines @@
     static bool IsValidPictInfo(const SkPictInfo& info);
     static SkPicture* Forwardport(const SkPictInfo&, const SkPictureData*);
 
     SkPictInfo createHeader() const;
     SkPictureData* backport() const;
 
     mutable uint32_t fUniqueID;
 };
 
 #endif