Discard atlas after every MultiPictureDraw::draw

src/gpu/GrLayerHoister.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrLayerHoister_DEFINED
 #define GrLayerHoister_DEFINED
 
@@ skipping 69 matching lines @@
         @param replacements Replacement object that will be used for a replacement draw
     */
     static void ConvertLayersToReplacements(const SkTDArray<GrHoistedLayer>& layers,
                                             GrReplacements* replacements);
 
     /** Unlock a group of layers in the layer cache.
         @param context    Owner of the layer cache (and thus the layers)
         @param layers     Unneeded layers in the atlas
     */
     static void UnlockLayers(GrContext* context, const SkTDArray<GrHoistedLayer>& layers);
+
+    /** Forceably remove all cached layers and release the atlas. Useful for debugging and timing.
+        This is only functional when GR_CACHE_HOISTED_LAYERS is set to 1 in GrLayerCache.h
+        @param context    Owner of the layer cache (and thus the layers)
+     */
+    static void PurgeCache(GrContext* context);
 };
 
 #endif