Overscroll and Elasticity for views::ScrollView

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 216 matching lines @@
   void set_num_unclipped_descendants(size_t descendants) {
     num_unclipped_descendants_ = descendants;
   }
   size_t num_unclipped_descendants() const {
     return num_unclipped_descendants_;
   }
 
   void SetScrollOffset(const gfx::ScrollOffset& scroll_offset);
 
   gfx::ScrollOffset scroll_offset() const { return inputs_.scroll_offset; }
-  void SetScrollOffsetFromImplSide(const gfx::ScrollOffset& scroll_offset);
+  void SetScrollOffsetFromImplSide(const gfx::ScrollOffset& scroll_offset,
+                                   gfx::Vector2dF* overscroll_delta);
 
-  void SetScrollClipLayerId(int clip_layer_id);
+  // TODO(tapted): Remove this overload.
+  void SetScrollClipLayerId(int clip_layer_id) {
+    SetScrollClipAndCanOverscroll(clip_layer_id, false);
+  }
+  void SetScrollClipAndCanOverscroll(int clip_layer_id, bool can_overscroll);
+
   bool scrollable() const { return inputs_.scroll_clip_layer_id != INVALID_ID; }
+  gfx::ScrollOffset overscroll() const { return inputs_.overscroll; }
   Layer* scroll_clip_layer() const;
 
   void SetUserScrollable(bool horizontal, bool vertical);
   bool user_scrollable_horizontal() const {
     return inputs_.user_scrollable_horizontal;
   }
   bool user_scrollable_vertical() const {
     return inputs_.user_scrollable_vertical;
   }
 
@@ skipping 22 matching lines @@
   }
 
   void SetForceRenderSurfaceForTesting(bool force_render_surface);
   bool force_render_surface_for_testing() const {
     return force_render_surface_for_testing_;
   }
 
   gfx::ScrollOffset CurrentScrollOffset() const {
     return inputs_.scroll_offset;
   }
+  gfx::ScrollOffset CurrentOverscroll() const { return inputs_.overscroll; }
 
   void SetDoubleSided(bool double_sided);
   bool double_sided() const { return inputs_.double_sided; }
 
   void SetShouldFlattenTransform(bool flatten);
   bool should_flatten_transform() const {
     return inputs_.should_flatten_transform;
   }
 
   bool Is3dSorted() const { return inputs_.sorting_context_id != 0; }
@@ skipping 361 matching lines @@
 
     bool use_parent_backface_visibility : 1;
 
     SkColor background_color;
 
     FilterOperations filters;
     FilterOperations background_filters;
     gfx::PointF filters_origin;
 
     gfx::ScrollOffset scroll_offset;
+    gfx::ScrollOffset overscroll;
 
     // This variable indicates which ancestor layer (if any) whose size,
     // transformed relative to this layer, defines the maximum scroll offset
     // for this layer.
     int scroll_clip_layer_id;
     bool user_scrollable_horizontal : 1;
     bool user_scrollable_vertical : 1;
+    bool can_overscroll : 1;
 
     uint32_t main_thread_scrolling_reasons;
     Region non_fast_scrollable_region;
 
     Region touch_event_handler_region;
 
     bool is_container_for_fixed_position_layers : 1;
     LayerPositionConstraint position_constraint;
 
     LayerStickyPositionConstraint sticky_position_constraint;
@@ skipping 55 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_