Remove SkBitmapHeap and SkBitmapHeapReader. They're unused.

src/core/SkPictureData.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPictureData_DEFINED
 #define SkPictureData_DEFINED
 
@@ skipping 135 matching lines @@
 private:
     void init();
 
     // these help us with reading/writing
     // Does not affect ownership of SkStream.
     bool parseStreamTag(SkStream*, uint32_t tag, uint32_t size,
                         SkPicture::InstallPixelRefProc, SkTypefacePlayback*);
     bool parseBufferTag(SkReadBuffer&, uint32_t tag, uint32_t size);
     void flattenToBuffer(SkWriteBuffer&) const;
 
-    // Only used by getBitmap() if the passed in index is SkBitmapHeap::INVALID_SLOT. This empty
-    // bitmap allows playback to draw nothing and move on.
-    SkBitmap fBadBitmap;
-
     SkTArray<SkBitmap> fBitmaps;
     SkTArray<SkPaint>  fPaints;
     SkTArray<SkPath>   fPaths;
 
     sk_sp<SkData>   fOpData;    // opcodes and parameters
 
     const SkPath    fEmptyPath;
     const SkBitmap  fEmptyBitmap;
 
     const SkPicture** fPictureRefs;
@@ skipping 12 matching lines @@
 
     const SkPictInfo fInfo;
 
     static void WriteFactories(SkWStream* stream, const SkFactorySet& rec);
     static void WriteTypefaces(SkWStream* stream, const SkRefCntSet& rec);
 
     void initForPlayback() const;
 };
 
 #endif