Converts MaximizeModeWindowManager to use ash/common types

ash/aura/wm_root_window_controller_aura.cc

Index: ash/aura/wm_root_window_controller_aura.cc
diff --git a/ash/aura/wm_root_window_controller_aura.cc b/ash/aura/wm_root_window_controller_aura.cc
index 1090768577ef1b7c76664bda46e360d5f26b6f12..0bb740fe290cc40c616c97bd878127047edba843 100644
--- a/ash/aura/wm_root_window_controller_aura.cc
+++ b/ash/aura/wm_root_window_controller_aura.cc
@@ -7,6 +7,7 @@
 #include "ash/aura/wm_shelf_aura.h"
 #include "ash/aura/wm_shell_aura.h"
 #include "ash/aura/wm_window_aura.h"
+#include "ash/common/wm/workspace/workspace_layout_manager_backdrop_delegate.h"
 #include "ash/common/wm_root_window_controller_observer.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/root_window_controller.h"
@@ -73,6 +74,12 @@ wm::WorkspaceWindowState WmRootWindowControllerAura::GetWorkspaceWindowState() {
   return root_window_controller_->workspace_controller()->GetWindowState();
 }
 
+void WmRootWindowControllerAura::SetMaximizeBackdropDelegate(
+    std::unique_ptr<WorkspaceLayoutManagerBackdropDelegate> delegate) {
+  root_window_controller_->workspace_controller()->SetMaximizeBackdropDelegate(
+      std::move(delegate));
+}
+
 AlwaysOnTopController* WmRootWindowControllerAura::GetAlwaysOnTopController() {
   return root_window_controller_->always_on_top_controller();
 }