Make browser windows override_redirect when dragging tabs.

ash/host/ash_window_tree_host_unified.cc

Index: ash/host/ash_window_tree_host_unified.cc
diff --git a/ash/host/ash_window_tree_host_unified.cc b/ash/host/ash_window_tree_host_unified.cc
index f94d1e277ed1a92baeb3add43a9dea36ad36214c..b95f7625358679f7bc887717d4d3a28c9f96ecb5 100644
--- a/ash/host/ash_window_tree_host_unified.cc
+++ b/ash/host/ash_window_tree_host_unified.cc
@@ -82,6 +82,8 @@ void AshWindowTreeHostUnified::RegisterMirroringHost(
 void AshWindowTreeHostUnified::ToggleFullScreen() {
 }
 
+void AshWindowTreeHostUnified::RemapAsNormalWindow() {}
+
 bool AshWindowTreeHostUnified::ConfineCursorToRootWindow() {
   return true;
 }