Implemented swipe to close in overview mode.

ash/wm/overview/scoped_transform_overview_window.h

Index: ash/wm/overview/scoped_transform_overview_window.h
diff --git a/ash/wm/overview/scoped_transform_overview_window.h b/ash/wm/overview/scoped_transform_overview_window.h
index b38f517b61a0a0b2d634e089e9c3639b179fa0ae..a84c2f8a7e71f86ec9c7cf1ed1486ea6d3ad880a 100644
--- a/ash/wm/overview/scoped_transform_overview_window.h
+++ b/ash/wm/overview/scoped_transform_overview_window.h
@@ -63,7 +63,6 @@ class ScopedTransformOverviewWindow
     return activate_button_.get();
   }
 
-
   // Starts an animation sequence which will use animation settings specified by
   // |animation_type|. The |animation_settings| container is populated with
   // scoped entities and the container should be destroyed at the end of the
@@ -114,10 +113,10 @@ class ScopedTransformOverviewWindow
 
   aura::Window* window() const { return window_; }
 
-  // Closes the transient root of the window managed by |this|.
-  void Close();
-
   // ash::TransparentActivateWindowButtonDelegate:
+  void Scroll(int delta_x) override;
+  void CancelScroll() override;
+  void Close() override;
   void Select() override;
 
  private: