Moves couple of WmShell methods to standalone functions

ash/common/wm/workspace/workspace_layout_manager.cc

Index: ash/common/wm/workspace/workspace_layout_manager.cc
diff --git a/ash/common/wm/workspace/workspace_layout_manager.cc b/ash/common/wm/workspace/workspace_layout_manager.cc
index 32f12937334181fce6e80fc9552b8e2c4e387568..88a70043811d311b4d80a5c18f1beed7de074553 100644
--- a/ash/common/wm/workspace/workspace_layout_manager.cc
+++ b/ash/common/wm/workspace/workspace_layout_manager.cc
@@ -24,6 +24,7 @@
 #include "ash/wm/screen_pinning_controller.h"
 #include "ash/wm/window_properties.h"
 #include "ash/wm/window_state_aura.h"
+#include "ash/wm/window_util.h"
 #include "base/command_line.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/base/ui_base_switches.h"
@@ -144,7 +145,7 @@ void WorkspaceLayoutManager::OnKeyboardBoundsChanging(
   if (!change_work_area)
     return;
 
-  WmWindow* window = shell_->GetActiveWindow();
+  WmWindow* window = WmWindow::Get(wm::GetActiveWindow());
   if (!window)
     return;