Make browser windows override_redirect when dragging tabs.

ash/host/ash_window_tree_host_x11.cc

Index: ash/host/ash_window_tree_host_x11.cc
diff --git a/ash/host/ash_window_tree_host_x11.cc b/ash/host/ash_window_tree_host_x11.cc
index a6971b5cae77d15f3d57308a5569a6b73eb76b7c..f44b422a792c1e09e5c24021e9ae4a958e33a0c6 100644
--- a/ash/host/ash_window_tree_host_x11.cc
+++ b/ash/host/ash_window_tree_host_x11.cc
@@ -126,6 +126,10 @@ gfx::Insets AshWindowTreeHostX11::GetHostInsets() const {
 
 aura::WindowTreeHost* AshWindowTreeHostX11::AsWindowTreeHost() { return this; }
 
+void AshWindowTreeHostX11::RemapAsNormalWindow() {
+  NOTREACHED();
+}
+
 void AshWindowTreeHostX11::PrepareForShutdown() {
   // Block the root window from dispatching events because it is weird for a
   // ScreenPositionClient not to be attached to the root window and for