Add VectorIconButton functionality to ImageButton.

ash/common/wm/overview/window_selector_item.h

Index: ash/common/wm/overview/window_selector_item.h
diff --git a/ash/common/wm/overview/window_selector_item.h b/ash/common/wm/overview/window_selector_item.h
index 097cc8b4971a22f2724f07bae45bb846b2e8a60d..24808a52f9c1c43059c77f372e04e1f95c8321fc 100644
--- a/ash/common/wm/overview/window_selector_item.h
+++ b/ash/common/wm/overview/window_selector_item.h
@@ -13,7 +13,6 @@
 #include "ui/aura/window_observer.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/rect.h"
-#include "ui/views/controls/button/button.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/widget/widget.h"
@@ -22,23 +21,19 @@ namespace gfx {
 class SlideAnimation;
 }
 
-namespace views {
-class ImageButton;
-}
-
 namespace ash {
 
 class WindowSelector;
 class WmWindow;
 
 // This class represents an item in overview mode.
-class ASH_EXPORT WindowSelectorItem : public views::ButtonListener,
+class ASH_EXPORT WindowSelectorItem : public views::ImageButtonDelegate,
                                       public aura::WindowObserver {
  public:
   // An image button with a close window icon.
   class OverviewCloseButton : public views::ImageButton {
    public:
-    explicit OverviewCloseButton(views::ButtonListener* listener);
+    explicit OverviewCloseButton(views::ImageButtonDelegate* listener);
     ~OverviewCloseButton() override;
 
     // Resets the listener so that the listener can go out of scope.
@@ -114,7 +109,7 @@ class ASH_EXPORT WindowSelectorItem : public views::ButtonListener,
 
   const gfx::Rect& target_bounds() const { return target_bounds_; }
 
-  // views::ButtonListener:
+  // views::ImageButtonDelegate:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   // aura::WindowObserver: