Add window property for restore bounds when virtual keyboard is enabled.

ash/mus/bridge/wm_window_mus.h

Index: ash/mus/bridge/wm_window_mus.h
diff --git a/ash/mus/bridge/wm_window_mus.h b/ash/mus/bridge/wm_window_mus.h
index cecb7e739ffbade6062ad201f32140baf2694673..5e34e3fc0160d7737f1a6cf4ff19d7b7e1b05065 100644
--- a/ash/mus/bridge/wm_window_mus.h
+++ b/ash/mus/bridge/wm_window_mus.h
@@ -135,6 +135,7 @@ class WmWindowMus : public WmWindow, public ui::WindowObserver {
   bool GetBoolProperty(WmWindowProperty key) override;
   int GetIntProperty(WmWindowProperty key) override;
   void SetIntProperty(WmWindowProperty key, int value) override;
+  gfx::Rect* GetRectProperty(WmWindowProperty key) override;
   ShelfItemDetails* GetShelfItemDetails() override;
   void SetShelfItemDetails(const ShelfItemDetails& details) override;
   void ClearShelfItemDetails() override;