cc: Fix low-res impl-side painting artifacts

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"
@@ skipping 11 matching lines @@
 class CC_EXPORT PicturePile {
 public:
   PicturePile();
   ~PicturePile();
 
   // Resize the PicturePile, invalidating / dropping recorded pictures as
   // necessary.
   void Resize(gfx::Size);
   gfx::Size size() const { return size_; }
 
+  void SetMinContentsScale(float min_contents_scale);
+
   // Re-record parts of the picture that are invalid.
   // 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:
   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_;
+  float min_contents_scale_;
+  int buffer_pixels_;
 
   DISALLOW_COPY_AND_ASSIGN(PicturePile);
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_PILE_H_