Refactors DimWindow and moves to ash/common

ash/wm/screen_pinning_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 "ash/wm/screen_pinning_controller.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/shell_window_ids.h"
+#include "ash/common/wm/window_dimmer.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/common/wm_window_observer.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/shell.h"
-#include "ash/wm/dim_window.h"
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "ui/aura/window_observer.h"
 
 namespace ash {
 namespace {
 
 WmWindow* CreateDimWindow(WmWindow* container) {
-  DimWindow* dim_window = new DimWindow(WmWindowAura::GetAuraWindow(container));
-  dim_window->SetDimOpacity(1);  // Set whole black.
-  WmWindow* result = WmWindowAura::Get(dim_window);
-  result->SetFullscreen();
-  result->Show();
-  return result;
+  // WindowDimmer is owned by |container|.
+  WindowDimmer* window_dimmer = new WindowDimmer(container);
+  window_dimmer->SetDimOpacity(1);  // Fully opaque.
+  window_dimmer->window()->SetFullscreen();
+  window_dimmer->window()->Show();
+  return window_dimmer->window();
 }
 
 // Returns a list of WmWindows corresponding to SystemModalContainers,
 // except ones whose root is shared with |pinned_window|.
 std::vector<WmWindow*> GetSystemModalWindowsExceptPinned(
     WmWindow* pinned_window) {
   WmWindow* pinned_root = pinned_window->GetRootWindow();
 
   std::vector<WmWindow*> result;
   for (WmWindow* system_modal :
@@ skipping 348 matching lines @@
   base::AutoReset<bool> auto_reset(&in_restacking_, true);
   for (WmWindow* dim_window : dim_windows_) {
     if (dim_window->GetParent() == container) {
       container->StackChildAtBottom(dim_window);
       break;
     }
   }
 }
 
 }  // namespace ash