Make PicturePile pile.

cc/picture_pile.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_H_
 #define CC_PICTURE_PILE_H_
 
+#include <list>
+
 #include "base/basictypes.h"
 #include "cc/cc_export.h"
 #include "cc/picture.h"
 #include "cc/region.h"
 #include "cc/scoped_ptr_vector.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 class PicturePileImpl;
@@ skipping 13 matching lines @@
   // Invalidations are in layer space.
   void Update(
       ContentLayerClient* painter,
       const Region& invalidation,
       RenderingStats& stats);
 
   // Update other with a shallow copy of this (main => compositor thread commit)
   void PushPropertiesTo(PicturePileImpl* other);
 
 private:
-  std::vector<scoped_refptr<Picture> > pile_;
+  friend class PicturePileImpl;
+
+  void InvalidateRect(gfx::Rect invalidation);
+  void ResetPile(ContentLayerClient* painter, RenderingStats& stats);
+
+  typedef std::list<scoped_refptr<Picture> > Pile;
+  Pile pile_;
   gfx::Size size_;
 
   DISALLOW_COPY_AND_ASSIGN(PicturePile);
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_PILE_H_