cc: Always keep the PictureLayerImpl::twin_layer_ pointer valid.

cc/debug/rasterize_and_record_benchmark_impl.cc

 // Copyright 2013 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.
 
 #include "cc/debug/rasterize_and_record_benchmark_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 91 matching lines @@
   PicturePileImpl* GetPile() override { return base_client_->GetPile(); }
 
   gfx::Size CalculateTileSize(const gfx::Size& content_bounds) const override {
     return base_client_->CalculateTileSize(content_bounds);
   }
 
   // This is the only function that returns something different from the base
   // client.
   const Region* GetInvalidation() override { return &invalidation_; }
 
-  const PictureLayerTiling* GetTwinTiling(
+  const PictureLayerTiling* GetPendingOrActiveTwinTiling(
       const PictureLayerTiling* tiling) const override {
-    return base_client_->GetTwinTiling(tiling);
+    return base_client_->GetPendingOrActiveTwinTiling(tiling);
   }
 
   PictureLayerTiling* GetRecycledTwinTiling(
       const PictureLayerTiling* tiling) override {
     return base_client_->GetRecycledTwinTiling(tiling);
   }
 
   size_t GetMaxTilesForInterestArea() const override {
     return base_client_->GetMaxTilesForInterestArea();
   }
@@ skipping 143 matching lines @@
       pixels_rasterized_with_non_solid_color(0),
       pixels_rasterized_as_opaque(0),
       total_layers(0),
       total_picture_layers(0),
       total_picture_layers_with_no_content(0),
       total_picture_layers_off_screen(0) {}
 
 RasterizeAndRecordBenchmarkImpl::RasterizeResults::~RasterizeResults() {}
 
 }  // namespace cc