[mus+ash] Removes WmWindow from ash/wm/mru_window_tracker and overview mode

ash/system/overview/overview_button_tray.cc

Index: ash/system/overview/overview_button_tray.cc
diff --git a/ash/system/overview/overview_button_tray.cc b/ash/system/overview/overview_button_tray.cc
index 0a9cc8f13dd361d52a0423fcc5dcf3d6660f4422..f4fb1ded48ea4c54c331e5c8fca5c43e9b85dc8f 100644
--- a/ash/system/overview/overview_button_tray.cc
+++ b/ash/system/overview/overview_button_tray.cc
@@ -15,7 +15,6 @@
 #include "ash/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/overview/window_selector_controller.h"
-#include "ash/wm_window.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/paint_vector_icon.h"
 #include "ui/views/border.h"
@@ -70,7 +69,7 @@ bool OverviewButtonTray::PerformAction(const ui::Event& event) {
       // current window), if it exists.
       if (mru_window_list.size() > 1) {
         AnimateInkDrop(views::InkDropState::DEACTIVATED, nullptr);
-        ::wm::ActivateWindow(WmWindow::GetAuraWindow(mru_window_list[1]));
+        ::wm::ActivateWindow(mru_window_list[1]);
         return true;
       }
     }