Revert of Discard atlas after every MultiPictureDraw::draw

src/core/SkMultiPictureDraw.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #if SK_SUPPORT_GPU
 #include "GrLayerHoister.h"
 #include "GrRecordReplaceDraw.h"
@@ skipping 128 matching lines @@
             fDrawData[i].canvas->drawPicture(fDrawData[i].picture,
                                              &fDrawData[i].matrix,
                                              fDrawData[i].paint);
         }
     }
 
 #ifndef SK_IGNORE_GPU_LAYER_HOISTING
     if (NULL != context) {
         GrLayerHoister::UnlockLayers(context, atlasedNeedRendering);
         GrLayerHoister::UnlockLayers(context, atlasedRecycled);
-#if !GR_CACHE_HOISTED_LAYERS
-        GrLayerHoister::PurgeCache(context);
-#endif
     }
 #endif
 
     this->reset();
 }