[ash-md] Fades overview header in and out

ash/common/wm/overview/window_grid.h

Index: ash/common/wm/overview/window_grid.h
diff --git a/ash/common/wm/overview/window_grid.h b/ash/common/wm/overview/window_grid.h
index 25f378847ca38e69dc94aa6b597d46339028d28d..587bd9e37d048246216fa6eb0a0534261cf641d5 100644
--- a/ash/common/wm/overview/window_grid.h
+++ b/ash/common/wm/overview/window_grid.h
@@ -161,8 +161,9 @@ class ASH_EXPORT WindowGrid : public WmWindowObserver {
                               int* min_right,
                               int* max_right);
 
-  // Returns the target bounds of the currently selected item.
-  const gfx::Rect GetSelectionBounds() const;
+  // Sets up WindowSelectorItem to use masks or shapes based on command flags.
+  // TODO(varkha): remove this in the next patch and use shapes but not masks.
+  void PrepareForUsingMasksOrShapes(size_t windows_count) const;
 
   // Root window the grid is in.
   WmWindow* root_window_;