Overscroll and Elasticity for views::ScrollView

cc/layers/layer_impl.h

 // Copyright 2011 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_IMPL_H_
 #define CC_LAYERS_LAYER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 280 matching lines @@
   void SetBounds(const gfx::Size& bounds);
   gfx::Size bounds() const;
   // Like bounds() but doesn't snap to int. Lossy on giant pages (e.g. millions
   // of pixels) due to use of single precision float.
   gfx::SizeF BoundsForScrolling() const;
   void SetBoundsDelta(const gfx::Vector2dF& bounds_delta);
   gfx::Vector2dF bounds_delta() const { return bounds_delta_; }
 
   void SetCurrentScrollOffset(const gfx::ScrollOffset& scroll_offset);
   gfx::ScrollOffset CurrentScrollOffset() const;
+  void SetCurrentOverscroll(const gfx::ScrollOffset& overscroll);
+  gfx::ScrollOffset CurrentOverscroll() const;
 
   gfx::ScrollOffset MaxScrollOffset() const;
   gfx::ScrollOffset ClampScrollOffsetToLimits(gfx::ScrollOffset offset) const;
   gfx::Vector2dF ClampScrollToMaxScrollOffset();
 
   // Returns the delta of the scroll that was outside of the bounds of the
   // initial scroll
   gfx::Vector2dF ScrollBy(const gfx::Vector2dF& scroll);
 
-  void SetScrollClipLayer(int scroll_clip_layer_id);
+  // TODO(tapted): Remove this overload.
+  void SetScrollClipLayer(int scroll_clip_layer_id) {
+    SetScrollClipAndCanOverscroll(scroll_clip_layer_id, false);
+  }
+  void SetScrollClipAndCanOverscroll(int scroll_clip_layer_id,
+                                     bool can_overscroll);
   int scroll_clip_layer_id() const { return scroll_clip_layer_id_; }
   LayerImpl* scroll_clip_layer() const;
   bool scrollable() const;
+  bool can_overscroll() const { return can_overscroll_; }
 
   void set_user_scrollable_horizontal(bool scrollable);
   bool user_scrollable_horizontal() const {
     return user_scrollable_horizontal_;
   }
   void set_user_scrollable_vertical(bool scrollable);
   bool user_scrollable_vertical() const { return user_scrollable_vertical_; }
 
   bool user_scrollable(ScrollbarOrientation orientation) const;
 
@@ skipping 179 matching lines @@
 
   // Properties synchronized from the associated Layer.
   gfx::Size bounds_;
   int scroll_clip_layer_id_;
 
   gfx::Vector2dF offset_to_transform_parent_;
   uint32_t main_thread_scrolling_reasons_;
 
   bool user_scrollable_horizontal_ : 1;
   bool user_scrollable_vertical_ : 1;
+  bool can_overscroll_ : 1;
   bool should_flatten_transform_from_property_tree_ : 1;
 
   // Tracks if drawing-related properties have changed since last redraw.
   bool layer_property_changed_ : 1;
   bool may_contain_video_ : 1;
 
   bool masks_to_bounds_ : 1;
   bool contents_opaque_ : 1;
   bool use_parent_backface_visibility_ : 1;
   bool use_local_transform_for_backface_visibility_ : 1;
@@ skipping 56 matching lines @@
   bool scrolls_drawn_descendant_ : 1;
   bool has_will_change_transform_hint_ : 1;
   bool needs_push_properties_ : 1;
 
   DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_IMPL_H_