Reland of [ash-md] Fades overview header in and out

ash/common/wm/overview/window_grid.h

 // Copyright 2014 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 ASH_COMMON_WM_OVERVIEW_WINDOW_GRID_H_
 #define ASH_COMMON_WM_OVERVIEW_WINDOW_GRID_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 143 matching lines @@
   // widest rows respectively. In-values of the |max_bottom|, |min_right| and
   // |max_right| parameters are ignored and their values are always initialized
   // inside this method. Returns true on success and false otherwise.
   bool FitWindowRectsInBounds(const gfx::Rect& bounds,
                               int height,
                               std::vector<gfx::Rect>* rects,
                               int* max_bottom,
                               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_;
 
   // Pointer to the window selector that spawned this grid.
   WindowSelector* window_selector_;
 
   // Vector containing all the windows in this grid.
   ScopedVector<WindowSelectorItem> window_list_;
 
@@ skipping 16 matching lines @@
 
   // True only after all windows have been prepared for overview.
   bool prepared_for_overview_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowGrid);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_OVERVIEW_WINDOW_GRID_H_