cc: Cleanup class/struct forward declarations

cc/debug/rasterize_and_record_benchmark.h

 // 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.
 
 #ifndef CC_DEBUG_RASTERIZE_AND_RECORD_BENCHMARK_H_
 #define CC_DEBUG_RASTERIZE_AND_RECORD_BENCHMARK_H_
 
 #include <stddef.h>
 
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/time/time.h"
 #include "cc/debug/micro_benchmark_controller.h"
 #include "cc/playback/recording_source.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace cc {
 
 class LayerTree;
-class Layer;
 
 class RasterizeAndRecordBenchmark : public MicroBenchmark {
  public:
   explicit RasterizeAndRecordBenchmark(
       std::unique_ptr<base::Value> value,
       const MicroBenchmark::DoneCallback& callback);
   ~RasterizeAndRecordBenchmark() override;
 
   // Implements MicroBenchmark interface.
   void DidUpdateLayers(LayerTree* layer_tree) override;
@@ skipping 23 matching lines @@
   bool main_thread_benchmark_done_;
 
   LayerTree* layer_tree_;
 
   base::WeakPtrFactory<RasterizeAndRecordBenchmark> weak_ptr_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_DEBUG_RASTERIZE_AND_RECORD_BENCHMARK_H_