Fix bug in GrCachedLayer reuse

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 "SkCanvas.h"
@@ skipping 36 matching lines @@
     if (needsRendering) {
         if (layer->isAtlased()) {
             hl = atlased->append();
         } else {
             hl = nonAtlased->append();
         }
     } else {
         hl = recycled->append();
     }
     
+    layerCache->addUse(layer);
     hl->fLayer = layer;
     hl->fPicture = pict;
     hl->fOffset = info.fOffset;
     hl->fCTM = info.fOriginXform;
 }
 
 // Return true if any layers are suitable for hoisting
 bool GrLayerHoister::FindLayersToHoist(GrContext* context,
                                        const SkPicture* topLevelPicture,
                                        const SkRect& query,
@@ skipping 189 matching lines @@
                             layer->start()+1, layer->stop(), initialCTM);
 
         layerCanvas->flush();
     }
 
     convert_layers_to_replacements(atlased, replacements);
     convert_layers_to_replacements(nonAtlased, replacements);
     convert_layers_to_replacements(recycled, replacements);
 }
 
-static void unlock_layer_in_cache(GrLayerCache* layerCache,
-                                  const SkPicture* picture,
-                                  GrCachedLayer* layer) {
-    layerCache->unlock(layer);
-
-#if DISABLE_CACHING
-    // 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->purge(picture->uniqueID());
-#endif
-}
-
 void GrLayerHoister::UnlockLayers(GrContext* context,
                                   const SkTDArray<GrHoistedLayer>& atlased,
                                   const SkTDArray<GrHoistedLayer>& nonAtlased,
                                   const SkTDArray<GrHoistedLayer>& recycled) {
     GrLayerCache* layerCache = context->getLayerCache();
 
     for (int i = 0; i < atlased.count(); ++i) {
-        unlock_layer_in_cache(layerCache, atlased[i].fPicture, atlased[i].fLayer);
+        layerCache->removeUse(atlased[i].fLayer);
     }
 
     for (int i = 0; i < nonAtlased.count(); ++i) {
-        unlock_layer_in_cache(layerCache, nonAtlased[i].fPicture, nonAtlased[i].fLayer);
+        layerCache->removeUse(nonAtlased[i].fLayer);
     }
 
     for (int i = 0; i < recycled.count(); ++i) {
-        unlock_layer_in_cache(layerCache, recycled[i].fPicture, recycled[i].fLayer);
+        layerCache->removeUse(recycled[i].fLayer);
     }
 
 #if DISABLE_CACHING
     // 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();)
 }