cc: Cleanup class/struct forward declarations

cc/layers/layer.h

 // Copyright 2010 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_H_
 #define CC_LAYERS_LAYER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 21 matching lines @@
 #include "cc/trees/target_property.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "third_party/skia/include/core/SkXfermode.h"
 #include "ui/gfx/geometry/point3_f.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 #include "ui/gfx/transform.h"
 
-namespace gfx {
-class BoxF;
-}
-
 namespace base {
 namespace trace_event {
 class ConvertableToTraceFormat;
 }
 }
 
 namespace cc {
 
 class CopyOutputRequest;
-class LayerAnimationEventObserver;
 class LayerClient;
 class LayerImpl;
 class LayerTreeHost;
 class LayerTreeHostCommon;
 class LayerTreeImpl;
-class LayerTreeSettings;
 class MutatorHost;
-class RenderingStatsInstrumentation;
-class ResourceUpdateQueue;
 class ScrollbarLayerInterface;
-class SimpleEnclosedRegion;
 
 namespace proto {
 class LayerNode;
 class LayerProperties;
-class LayerUpdate;
 }  // namespace proto
 
 // Base class for composited layers. Special layer types are derived from
 // this class.
 class CC_EXPORT Layer : public base::RefCounted<Layer> {
  public:
   using LayerListType = LayerList;
   using LayerIdMap = std::unordered_map<int, scoped_refptr<Layer>>;
 
   enum LayerIdLabels {
@@ skipping 620 matching lines @@
   // These all act like draw properties, so don't need push properties.
   gfx::Rect visible_layer_rect_;
   size_t num_unclipped_descendants_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_H_