Converts MaximizeModeWindowManager to use ash/common types

ash/mus/bridge/wm_root_window_controller_mus.cc

Index: ash/mus/bridge/wm_root_window_controller_mus.cc
diff --git a/ash/mus/bridge/wm_root_window_controller_mus.cc b/ash/mus/bridge/wm_root_window_controller_mus.cc
index 64c69fa64aa3b04f34093a7e1124be819bc3141f..3c226368a4809e3089015548142bb086257720d1 100644
--- a/ash/mus/bridge/wm_root_window_controller_mus.cc
+++ b/ash/mus/bridge/wm_root_window_controller_mus.cc
@@ -4,6 +4,8 @@
 
 #include "ash/mus/bridge/wm_root_window_controller_mus.h"
 
+#include "ash/common/wm/workspace/workspace_layout_manager.h"
+#include "ash/common/wm/workspace/workspace_layout_manager_backdrop_delegate.h"
 #include "ash/common/wm_root_window_controller_observer.h"
 #include "ash/mus/bridge/wm_shelf_mus.h"
 #include "ash/mus/bridge/wm_shell_mus.h"
@@ -92,6 +94,12 @@ wm::WorkspaceWindowState WmRootWindowControllerMus::GetWorkspaceWindowState() {
   return wm::WORKSPACE_WINDOW_STATE_DEFAULT;
 }
 
+void WmRootWindowControllerMus::SetMaximizeBackdropDelegate(
+    std::unique_ptr<WorkspaceLayoutManagerBackdropDelegate> delegate) {
+  root_window_controller_->workspace_layout_manager()
+      ->SetMaximizeBackdropDelegate(std::move(delegate));
+}
+
 AlwaysOnTopController* WmRootWindowControllerMus::GetAlwaysOnTopController() {
   return root_window_controller_->always_on_top_controller();
 }