cc: Cleanup class/struct forward declarations

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 34 matching lines @@
 namespace base {
 namespace trace_event {
 class ConvertableToTraceFormat;
 class TracedValue;
 }
 class DictionaryValue;
 }
 
 namespace cc {
 
-class LayerTreeHostImpl;
 class LayerTreeImpl;
 class MicroBenchmarkImpl;
 class MutatorHost;
-class Occlusion;
-class EffectTree;
 class PrioritizedTile;
 class RenderPass;
-class RenderPassId;
-class Renderer;
 class ScrollbarLayerImplBase;
 class SimpleEnclosedRegion;
 class Tile;
-class TransformTree;
 class ScrollState;
 
 struct AppendQuadsData;
 
 enum DrawMode {
   DRAW_MODE_NONE,
   DRAW_MODE_HARDWARE,
   DRAW_MODE_SOFTWARE,
   DRAW_MODE_RESOURCELESS_SOFTWARE
 };
@@ skipping 502 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_