Refactor backdrop that is currently used in the maximized mode.

ash/ash_touch_exploration_manager_chromeos.cc

 // 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.
 
 #include "ash/ash_touch_exploration_manager_chromeos.h"
 
 #include "ash/accessibility_delegate.h"
 #include "ash/root_window_controller.h"
 #include "ash/shared/app_types.h"
 #include "ash/shell.h"
@@ skipping 149 matching lines @@
   }
 
   if (spoken_feedback_enabled) {
     if (!touch_exploration_controller_.get()) {
       touch_exploration_controller_ =
           base::MakeUnique<ui::TouchExplorationController>(
               root_window_controller_->GetRootWindow(), this,
               touch_accessibility_enabler_.get());
     }
     if (pass_through_surface) {
-      const gfx::Rect& work_area = root_window_controller_->GetWindow()
-                                       ->GetDisplayNearestWindow()
-                                       .work_area();
+      const gfx::Rect work_area = root_window_controller_->GetWindow()
+                                      ->GetDisplayNearestWindow()
+                                      .work_area();
       touch_exploration_controller_->SetExcludeBounds(work_area);
       SilenceSpokenFeedback();
       Shell::Get()->accessibility_delegate()->ClearFocusHighlight();
     } else {
       touch_exploration_controller_->SetExcludeBounds(gfx::Rect());
     }
   } else {
     touch_exploration_controller_.reset();
   }
 }
 
 bool AshTouchExplorationManager::VolumeAdjustSoundEnabled() {
   return !base::CommandLine::ForCurrentProcess()->HasSwitch(
       chromeos::switches::kDisableVolumeAdjustSound);
 }
 
 }  // namespace ash