Add ability to underline links on hover in Views

ui/views/controls/link.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_LINK_H_
 #define UI_VIEWS_CONTROLS_LINK_H_
 
 #include <string>
 
 #include "ui/views/controls/label.h"
@@ skipping 21 matching lines @@
 
   // Overridden from View:
   virtual void OnEnabledChanged() OVERRIDE;
   virtual std::string GetClassName() const OVERRIDE;
   virtual gfx::NativeCursor GetCursor(const ui::MouseEvent& event) OVERRIDE;
   virtual bool HitTestRect(const gfx::Rect& rect) const OVERRIDE;
   virtual bool OnMousePressed(const ui::MouseEvent& event) OVERRIDE;
   virtual bool OnMouseDragged(const ui::MouseEvent& event) OVERRIDE;
   virtual void OnMouseReleased(const ui::MouseEvent& event) OVERRIDE;
   virtual void OnMouseCaptureLost() OVERRIDE;
+  virtual void OnMouseEntered(const ui::MouseEvent& event) OVERRIDE;
+  virtual void OnMouseExited(const ui::MouseEvent& event) OVERRIDE;
+
   virtual ui::EventResult OnGestureEvent(
       const ui::GestureEvent& event) OVERRIDE;
   virtual bool OnKeyPressed(const ui::KeyEvent& event) OVERRIDE;
   virtual bool SkipDefaultKeyEventProcessing(
       const ui::KeyEvent& event) OVERRIDE;
   virtual void GetAccessibleState(ui::AccessibleViewState* state) OVERRIDE;
 
   // Overridden from Label:
   virtual void SetFont(const gfx::Font& font) OVERRIDE;
 
   virtual void SetEnabledColor(SkColor color) OVERRIDE;
   void SetPressedColor(SkColor color);
+  void SetUnderlineOnHover(bool underline_on_hover);
 
   static const char kViewClassName[];
 
  private:
   void Init();
 
   void SetPressed(bool pressed);
 
   void RecalculateFont();
 
   LinkListener* listener_;
 
   // Whether the link is currently pressed.
   bool pressed_;
 
+  // Whether the link is underlined only on hover.
+  bool underline_on_hover_;
+
+  // Whether the mouse is hovering over the link.
+  bool mouse_inside_;
+
   // The color when the link is neither pressed nor disabled.
   SkColor requested_enabled_color_;
 
   // The color when the link is pressed.
   SkColor requested_pressed_color_;
 
   DISALLOW_COPY_AND_ASSIGN(Link);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_LINK_H_