Make PicturePile pile.

cc/picture_pile_impl.h

 // Copyright 2012 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_PICTURE_PILE_IMPL_H_
 #define CC_PICTURE_PILE_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "cc/cc_export.h"
 #include "cc/picture.h"
+#include "cc/picture_pile.h"
 #include "cc/scoped_ptr_vector.h"
 #include "ui/gfx/rect.h"
 
 namespace cc {
-class PicturePile;
 struct RenderingStats;
 
 class CC_EXPORT PicturePileImpl : public base::RefCounted<PicturePileImpl> {
 public:
   static scoped_refptr<PicturePileImpl> Create();
 
   // Clone a paint-safe version of this picture.
   scoped_refptr<PicturePileImpl> CloneForDrawing() const;
 
   // Raster a subrect of this PicturePileImpl into the given canvas.
   // It's only safe to call paint on a cloned version.
   // It is assumed that contentsScale has already been applied to this canvas.
   void Raster(SkCanvas* canvas, gfx::Rect rect, RenderingStats* stats);
 
 private:
   friend class PicturePile;
 
   PicturePileImpl();
   ~PicturePileImpl();
 
-  std::vector<scoped_refptr<Picture> > pile_;
+  PicturePile::Pile pile_;
 
   friend class base::RefCounted<PicturePileImpl>;
   DISALLOW_COPY_AND_ASSIGN(PicturePileImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_PILE_IMPL_H_