mash: remove more shell/shelf WmWindow usage.

ash/app_list/app_list_delegate_impl.cc

Index: ash/app_list/app_list_delegate_impl.cc
diff --git a/ash/app_list/app_list_delegate_impl.cc b/ash/app_list/app_list_delegate_impl.cc
index ee61b8023afd3dff3cac333fc48935c9efd2c49d..57f7a5c7b585cebd5f2187f751dd4bd206294392 100644
--- a/ash/app_list/app_list_delegate_impl.cc
+++ b/ash/app_list/app_list_delegate_impl.cc
@@ -10,6 +10,7 @@
 #include "ash/shelf/wm_shelf.h"
 #include "ash/shell.h"
 #include "ash/shell_port.h"
+#include "ash/wm_window.h"
 #include "ui/app_list/presenter/app_list.h"
 
 namespace ash {
@@ -24,8 +25,8 @@ AppListDelegateImpl::~AppListDelegateImpl() {
 
 void AppListDelegateImpl::OnAppListVisibilityChanged(bool visible,
                                                      int64_t display_id) {
-  WmWindow* root_window =
-      ShellPort::Get()->GetRootWindowForDisplayId(display_id);
+  aura::Window* root_window =
+      ShellPort::Get()->GetRootWindowForDisplayId(display_id)->aura_window();

[James Cook, 2017/05/17 23:41:49]

optional: Do you think it makes sense to change
ShellPort::GetRootWindowForDisplayId() to return aura::Window* in this CL? It
seems like you're touching a lot of the call sites already.

[msw, 2017/05/18 20:28:00]

Done.

   AppListButton* app_list_button =
       WmShelf::ForWindow(root_window)->shelf_widget()->GetAppListButton();
   if (!app_list_button)