Replace WmWindowObserver with aura::WindowObserver.

ash/common/test/test_shelf_delegate.cc

Index: ash/common/test/test_shelf_delegate.cc
diff --git a/ash/common/test/test_shelf_delegate.cc b/ash/common/test/test_shelf_delegate.cc
index d0f21f0c51190495a36122f35fa2996416e8ba6b..24a1ad503cc4f3ee0c5e045f6d5861f3482082c6 100644
--- a/ash/common/test/test_shelf_delegate.cc
+++ b/ash/common/test/test_shelf_delegate.cc
@@ -15,6 +15,7 @@
 #include "ash/common/wm_window_property.h"
 #include "ash/root_window_controller.h"
 #include "base/memory/ptr_util.h"
+#include "ui/aura/window.h"
 
 namespace ash {
 namespace test {
@@ -75,7 +76,7 @@ void TestShelfDelegate::AddShelfItem(WmWindow* window, ShelfItemStatus status) {
   ShelfID id = model->next_id();
   item.status = status;
   model->Add(item);
-  window->AddObserver(this);
+  window->aura_window()->AddObserver(this);
 
   model->SetShelfItemDelegate(id,
                               base::MakeUnique<TestShelfItemDelegate>(window));
@@ -90,7 +91,7 @@ void TestShelfDelegate::RemoveShelfItemForWindow(WmWindow* window) {
   int index = model->ItemIndexByID(shelf_id);
   DCHECK_NE(-1, index);
   model->RemoveItemAt(index);
-  window->RemoveObserver(this);
+  window->aura_window()->RemoveObserver(this);
   if (HasShelfIDToAppIDMapping(shelf_id)) {
     const std::string& app_id = GetAppIDForShelfID(shelf_id);
     if (IsAppPinned(app_id))
@@ -100,17 +101,17 @@ void TestShelfDelegate::RemoveShelfItemForWindow(WmWindow* window) {
   }
 }
 
-void TestShelfDelegate::OnWindowDestroying(WmWindow* window) {
-  RemoveShelfItemForWindow(window);
+void TestShelfDelegate::OnWindowDestroying(aura::Window* window) {
+  RemoveShelfItemForWindow(WmWindow::Get(window));
 }
 
-void TestShelfDelegate::OnWindowTreeChanging(WmWindow* window,
-                                             const TreeChangeParams& params) {
+void TestShelfDelegate::OnWindowHierarchyChanging(
+    const HierarchyChangeParams& params) {
   // The window may be legitimately reparented while staying open if it moves
   // to another display or container. If the window does not have a new parent
   // then remove the shelf item.
   if (!params.new_parent)
-    RemoveShelfItemForWindow(params.target);
+    RemoveShelfItemForWindow(WmWindow::Get(params.target));
 }
 
 ShelfID TestShelfDelegate::GetShelfIDForAppID(const std::string& app_id) {