hide discardable factory from public imagegenerator api

tools/LazyDecodeBitmap.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "LazyDecodeBitmap.h"
 
 #include "SkData.h"
 #include "SkDecodingImageGenerator.h"
 #include "SkDiscardableMemoryPool.h"
-#include "SkImageGenerator.h"
+#include "SkImageGeneratorPriv.h"
 #include "SkForceLinking.h"
 
 #include "SkCommandLineFlags.h"
 
 __SK_FORCE_IMAGE_DECODER_LINKING;
 
 DEFINE_bool(useVolatileCache, false, "Use a volatile cache for deferred image decoding pixels. "
             "Only meaningful if --deferImageDecoding is set to true and the platform has an "
             "implementation.");
 
@@ skipping 16 matching lines @@
     }
     SkDiscardableMemory::Factory* pool = NULL;
     if ((!FLAGS_useVolatileCache) || (info.fWidth * info.fHeight < 32 * 1024)) {
         // how to do switching with SkDiscardableMemory.
         pool = SkGetGlobalDiscardableMemoryPool();
         // Only meaningful if platform has a default discardable
         // memory implementation that differs from the global DM pool.
     }
     return SkInstallDiscardablePixelRef(gen.detach(), dst, pool);
 }