Improving the appearance of overlay scrollbars

ui/views/controls/scrollbar/scroll_bar.h

 // Copyright (c) 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 UI_VIEWS_CONTROLS_SCROLLBAR_SCROLL_BAR_H_
 #define UI_VIEWS_CONTROLS_SCROLLBAR_SCROLL_BAR_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/views/view.h"
@@ skipping 63 matching lines @@
   // current position
   virtual void Update(int viewport_size, int content_size, int current_pos);
 
   // Returns the max and min positions.
   int GetMaxPosition() const;
   int GetMinPosition() const;
 
   // Returns the position of the scrollbar.
   virtual int GetPosition() const = 0;
 
-  // Get the width or height of this scrollbar, for use in layout calculations.
-  // For a vertical scrollbar, this is the width of the scrollbar, likewise it
-  // is the height for a horizontal scrollbar.
-  virtual int GetLayoutSize() const = 0;
+  // Get the width or height of this scrollbar. For a vertical scrollbar, this
+  // is the width of the scrollbar, likewise it is the height for a horizontal
+  // scrollbar.
+  virtual int GetThickness() const = 0;
 
-  // Get the width or height for this scrollbar which overlaps with the content.
-  // Default is 0.
-  virtual int GetContentOverlapSize() const;
+  // Returns true if the scrollbar should sit on top of the content area (e.g.
+  // for overlay scrollbars).
+  virtual bool OverlapsContent() const = 0;
 
   // Called when a ScrollEvent (in any, or no, direction) is seen by the parent
   // ScrollView. E.g., this may reveal an overlay scrollbar to indicate
   // possible scrolling directions to the user.
   virtual void ObserveScrollEvent(const ui::ScrollEvent& event);
 
  protected:
   // Create new scrollbar, either horizontal or vertical. These are protected
   // since you need to be creating either a NativeScrollBar or a
   // ImageScrollBar.
   explicit ScrollBar(bool is_horiz);
 
  private:
   const bool is_horiz_;
 
   ScrollBarController* controller_;
 
   int max_pos_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollBar);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SCROLLBAR_SCROLL_BAR_H_