Discard atlas after every MultiPictureDraw::draw

src/gpu/GrLayerHoister.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.
  */
 
 #include "GrLayerCache.h"
 #include "GrLayerHoister.h"
 #include "GrRecordReplaceDraw.h"
@@ skipping 296 matching lines @@
 }
 
 void GrLayerHoister::UnlockLayers(GrContext* context,
                                   const SkTDArray<GrHoistedLayer>& layers) {
     GrLayerCache* layerCache = context->getLayerCache();
 
     for (int i = 0; i < layers.count(); ++i) {
         layerCache->removeUse(layers[i].fLayer);
     }
 
-#if DISABLE_CACHING
+    SkDEBUGCODE(layerCache->validate();)
+}
+
+void GrLayerHoister::PurgeCache(GrContext* context) {
+#if !GR_CACHE_HOISTED_LAYERS
+    GrLayerCache* layerCache = context->getLayerCache();
+
     // This code completely clears out the atlas. It is required when
     // caching is disabled so the atlas doesn't fill up and force more
     // free floating layers
     layerCache->purgeAll();
 #endif
-
-    SkDEBUGCODE(layerCache->validate();)
 }
-