cc: Generate tilings at other scales for impl-side painting

cc/picture_layer_tiling_set.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_LAYER_TILING_SET_H_
 #define CC_PICTURE_LAYER_TILING_SET_H_
 
 #include "cc/picture_layer_tiling.h"
 #include "cc/region.h"
 #include "cc/scoped_ptr_vector.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 
 class CC_EXPORT PictureLayerTilingSet {
  public:
   PictureLayerTilingSet(PictureLayerTilingClient* client);
   ~PictureLayerTilingSet();
 
   // Shallow copies all data (except client and bounds from other).
   void CloneAll(
      const PictureLayerTilingSet& other,
      const Region& invalidation);
   void Clone(const PictureLayerTiling* tiling, const Region& invalidation);
 
   void SetLayerBounds(gfx::Size layer_bounds);
   gfx::Size LayerBounds() const;
 
-  const PictureLayerTiling* AddTiling(
+  PictureLayerTiling* AddTiling(
       float contents_scale,
       gfx::Size tile_size);
   size_t num_tilings() const { return tilings_.size(); }
   PictureLayerTiling* tiling_at(size_t idx) { return tilings_[idx]; }
 
+  // Remove all tilings.
+  void RemoveAll();
+
+  // Remove one tiling.
+  void Remove(PictureLayerTiling* tiling);
+
+  // Remove all tiles, but keep all tilings.
   void Reset();
 
   void UpdateTilePriorities(
       WhichTree tree,
       const gfx::Size& device_viewport,
       float layer_content_scale_x,
       float layer_content_scale_y,
       const gfx::Transform& last_screen_transform,
       const gfx::Transform& current_screen_transform,
       double time_delta);
 
   // For a given rect, iterates through tiles that can fill it.  If no
   // set of tiles with resources can fill the rect, then it will iterate
   // through null tiles with valid geometry_rect() until the rect is full.
   // If all tiles have resources, the union of all geometry_rects will
   // exactly fill rect with no overlap.
   class CC_EXPORT Iterator {
    public:
     Iterator(
       const PictureLayerTilingSet* set,
       float contents_scale,
-      gfx::Rect rect);
+      gfx::Rect content_rect,
+      float ideal_contents_scale);
     ~Iterator();
 
     // Visible rect (no borders), always in the space of rect,
     // regardless of the relative contents scale of the tiling.
     gfx::Rect geometry_rect() const;
     // Texture rect (in texels) for geometry_rect
     gfx::RectF texture_rect() const;
     // Texture size in texels
     gfx::Size texture_size() const;
 
     Tile* operator->() const;
     Tile* operator*() const;
 
     Iterator& operator++();
     operator bool() const;
 
+    PictureLayerTiling* CurrentTiling();
+
    private:
+    int NextTiling() const;
+
     const PictureLayerTilingSet* set_;
     float contents_scale_;
+    float ideal_contents_scale_;
     PictureLayerTiling::Iterator tiling_iter_;
     int current_tiling_;
+    int ideal_tiling_;
 
     Region current_region_;
     Region missing_region_;
     Region::Iterator region_iter_;
   };
 
  private:
   PictureLayerTilingClient* client_;
   gfx::Size layer_bounds_;
   ScopedPtrVector<PictureLayerTiling> tilings_;
   Region invalidation_;
 
   friend class Iterator;
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_LAYER_TILING_SET_H_