Centralizes more shared code between ash and mash

ash/mus/bridge/wm_root_window_controller_mus.cc

Index: ash/mus/bridge/wm_root_window_controller_mus.cc
diff --git a/ash/mus/bridge/wm_root_window_controller_mus.cc b/ash/mus/bridge/wm_root_window_controller_mus.cc
index 46531b5132d956947ab7843e360a1582200b930f..28f7425222e3ad53d703ac29ff3838661770a6e7 100644
--- a/ash/mus/bridge/wm_root_window_controller_mus.cc
+++ b/ash/mus/bridge/wm_root_window_controller_mus.cc
@@ -75,6 +75,10 @@ const display::Display& WmRootWindowControllerMus::GetDisplay() const {
   return root_window_controller_->display();
 }
 
+void WmRootWindowControllerMus::MoveWindowsTo(WmWindow* dest) {
+  WmRootWindowController::MoveWindowsTo(dest);
+}
+
 bool WmRootWindowControllerMus::HasShelf() {
   return GetShelf() != nullptr;
 }
@@ -83,10 +87,6 @@ WmShell* WmRootWindowControllerMus::GetShell() {
   return shell_;
 }
 
-AlwaysOnTopController* WmRootWindowControllerMus::GetAlwaysOnTopController() {
-  return root_window_controller_->always_on_top_controller();
-}
-
 WmShelf* WmRootWindowControllerMus::GetShelf() {
   return root_window_controller_->wm_shelf();
 }
@@ -127,5 +127,12 @@ gfx::Point WmRootWindowControllerMus::GetLastMouseLocationInRoot() {
   return location;
 }
 
+bool WmRootWindowControllerMus::ShouldDestroyWindowInCloseChildWindows(
+    WmWindow* window) {
+  ui::Window* ui_window = WmWindowMus::GetMusWindow(window);
+  return ui_window->WasCreatedByThisClient() ||
+         ui_window->window_tree()->GetRoots().count(ui_window);

[James Cook, 2016/09/21 22:03:18]

Question for my knowledge: So we don't have a concept of not-owned-by-parent for
ui::Window?  (And that's what makes unit tests hard?)

[sky, 2016/09/21 22:47:49]

Currently ui::Window doesn't own it's children, so not-owned-by-parent doesn't
apply to ui::Window. I filed 647513 for this. I see two possibilities:
. We change ownership of ui::Window to match aura::Window.
. We make WmWindowMus own it's children (to mirror aura).

But I may be misunderstanding your question. If you're asking why we can't make
tests have code like:

std::unique_ptr<WmWindow> window;

It's because WmWindow is owned by the corresponding ui::Window or aura::Window.
We could introduce a different ownership model e.g. something like
WINDOWS_OWNS_NATIVE_WINDOW and NATIVE_WINDOW_OWNS_WINDOW, but it would only be
for tests and result in a much different shutdown flow than is normally seen.

Does that answer your question?

+}
+
 }  // namespace mus
 }  // namespace ash