[ash-md] Erases the pre-MD code path for Overview Mode

ash/common/material_design/material_design_controller.h

 // Copyright 2016 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_MATERIAL_DESIGN_MATERIAL_DESIGN_CONTROLLER_H_
 #define ASH_COMMON_MATERIAL_DESIGN_MATERIAL_DESIGN_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
 
@@ skipping 19 matching lines @@
   };
 
   // Initializes |mode_|. Must be called before calling IsMaterial(),
   // IsMaterialExperimental(), IsMaterialNormal(), or GetMode().
   static void Initialize();
 
   // Returns the currently initialized MaterialDesignController::Mode type for
   // Chrome OS system UI.
   static Mode GetMode();
 
-  // Returns true if overview mode is using Material Design.
-  static bool IsOverviewMaterial();
-
   // Returns true if Material Design features are enabled for Chrome OS shelf.
   static bool IsShelfMaterial();
 
   // Returns true if Material Design features are enabled for Chrome OS
   // immersive mode.
   static bool IsImmersiveModeMaterial();
 
   // Returns true if Material Design features are enabled for Chrome OS system
   // tray menu.
   static bool IsSystemTrayMenuMaterial();
@@ skipping 34 matching lines @@
   // Resets the initialization state to uninitialized. To be used by tests to
   // allow calling Initialize() more than once.
   static void Uninitialize();
 
   DISALLOW_COPY_AND_ASSIGN(MaterialDesignController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_MATERIAL_DESIGN_MATERIAL_DESIGN_CONTROLLER_H_