Don't free non-tile resources on GPU rasterization toggle

cc/layers/layer_impl.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_LAYER_IMPL_H_
 #define CC_LAYERS_LAYER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 357 matching lines @@
 
   void ResetChangeTracking();
 
   virtual SimpleEnclosedRegion VisibleOpaqueRegion() const;
 
   virtual void DidBecomeActive() {}
 
   virtual void DidBeginTracing();
 
   // Release resources held by this layer. Called when the output surface
-  // that rendered this layer was lost or a rendering mode switch has occured.
+  // that rendered this layer was lost.
   virtual void ReleaseResources();
 
-  // Recreate resources that are required after they were released by a
-  // ReleaseResources call.
-  virtual void RecreateResources();
+  // Release tile resources held by this layer. Called when a rendering mode
+  // switch has occured and tiles are no longer valid.
+  virtual void ReleaseTileResources();
+
+  // Recreate tile resources held by this layer after they were released by a
+  // ReleaseTileResources call.
+  virtual void RecreateTileResources();
 
   virtual std::unique_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl);
   virtual bool IsSnapped();
   virtual void PushPropertiesTo(LayerImpl* layer);
 
   virtual void GetAllPrioritizedTilesForTracing(
       std::vector<PrioritizedTile>* prioritized_tiles) const;
   virtual void AsValueInto(base::trace_event::TracedValue* dict) const;
 
   virtual size_t GPUMemoryUsageInBytes() const;
@@ skipping 186 matching lines @@
   bool has_will_change_transform_hint_ : 1;
   bool needs_push_properties_ : 1;
   bool scrollbars_hidden_ : 1;
 
   DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_IMPL_H_