mash: Migrate ShellDelegate ownership and access to WmShell.

ash/mus/window_manager.cc

Index: ash/mus/window_manager.cc
diff --git a/ash/mus/window_manager.cc b/ash/mus/window_manager.cc
index 3f11af23b86cb72b530d135b27f477c807baf898..9d0447c63e44387973ac83fdc74a1227fbc602d0 100644
--- a/ash/mus/window_manager.cc
+++ b/ash/mus/window_manager.cc
@@ -68,7 +68,7 @@ void WindowManager::Init(::ui::WindowTreeClient* window_tree_client) {
   window_manager_client_->SetFrameDecorationValues(
       std::move(frame_decoration_values));
 
-  shell_.reset(new WmShellMus(window_tree_client_));
+  shell_.reset(new WmShellMus(nullptr, window_tree_client_));

[James Cook, 2016/07/06 21:27:27]

Put a TODO here explaining that the nullptr is the delegate and will need to be
fixed.

[msw, 2016/07/06 21:58:55]

Done.

   lookup_.reset(new WmLookupMus);
 }