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

ash/common/material_design/material_design_controller.cc

 // 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.
 
 #include <string>
 
 #include "ash/common/ash_switches.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 40 matching lines @@
 #endif  // OS_CHROMEOS
 }
 
 // static
 MaterialDesignController::Mode MaterialDesignController::GetMode() {
   DCHECK_NE(mode_, Mode::UNINITIALIZED);
   return mode_;
 }
 
 // static
-bool MaterialDesignController::IsOverviewMaterial() {
-  return MaterialDesignController::IsMaterial();
-}
-
-// static
 bool MaterialDesignController::IsShelfMaterial() {
   return MaterialDesignController::IsMaterialExperimental();
 }
 
 // static
 bool MaterialDesignController::IsImmersiveModeMaterial() {
   return IsMaterial();
 }
 
 // static
@@ skipping 35 matching lines @@
 void MaterialDesignController::SetMode(Mode mode) {
   mode_ = mode;
 }
 
 // static
 void MaterialDesignController::Uninitialize() {
   mode_ = Mode::UNINITIALIZED;
 }
 
 }  // namespace ash