Makes Panel related classes use ash/wm/common types

ash/wm/workspace_controller_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/wm/workspace_controller.h"
 
 #include <map>
 
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
@@ skipping 110 matching lines @@
   aura::Window* CreateTestPanel(aura::WindowDelegate* delegate,
                                 const gfx::Rect& bounds) {
     aura::Window* window = CreateTestWindowInShellWithDelegateAndType(
         delegate,
         ui::wm::WINDOW_TYPE_PANEL,
         0,
         bounds);
     test::TestShelfDelegate* shelf_delegate =
         test::TestShelfDelegate::instance();
     shelf_delegate->AddShelfItem(window);
-    PanelLayoutManager* manager = static_cast<PanelLayoutManager*>(
-        Shell::GetContainer(window->GetRootWindow(),
-                            kShellWindowId_PanelContainer)->layout_manager());
+    PanelLayoutManager* manager =
+        PanelLayoutManager::Get(wm::WmWindowAura::Get(window));
     manager->Relayout();
     return window;
   }
 
   aura::Window* GetDesktop() {
     return Shell::GetContainer(Shell::GetPrimaryRootWindow(),
                                kShellWindowId_DefaultContainer);
   }
 
   gfx::Rect GetFullscreenBounds(aura::Window* window) {
@@ skipping 1465 matching lines @@
                          ui::EventTimeForNow());
     target = targeter->FindTargetForEvent(root, &touch);
     if (points[i].is_target_hit)
       EXPECT_EQ(window.get(), target);
     else
       EXPECT_NE(window.get(), target);
   }
 }
 
 }  // namespace ash