Remove persisted docked windows

ui/views/widget/native_widget_aura.cc

Index: ui/views/widget/native_widget_aura.cc
diff --git a/ui/views/widget/native_widget_aura.cc b/ui/views/widget/native_widget_aura.cc
index 8082fb5a3f3c295563e9e92fbd9c92da36ca445d..2d0345b4f32a2abbd745e34ce6b412b19ba1d9b9 100644
--- a/ui/views/widget/native_widget_aura.cc
+++ b/ui/views/widget/native_widget_aura.cc
@@ -536,6 +536,7 @@ void NativeWidgetAura::ShowWithWindowState(ui::WindowShowState state) {
 
   if (state == ui::SHOW_STATE_MAXIMIZED || state == ui::SHOW_STATE_FULLSCREEN ||
       state == ui::SHOW_STATE_DOCKED) {
+    // TODO(afakhry): Remove in M58.
     window_->SetProperty(aura::client::kShowStateKey, state);
   }
   window_->Show();
@@ -993,6 +994,7 @@ NativeWidgetAura::~NativeWidgetAura() {
 // NativeWidgetAura, private:
 
 bool NativeWidgetAura::IsDocked() const {
+  // TODO(afakhry): Remove in M58.
   return window_ &&
          window_->GetProperty(aura::client::kShowStateKey) ==
              ui::SHOW_STATE_DOCKED;