Desktop aura: Break aura::Window::SetParent in two.

ash/wm/workspace/workspace_window_resizer_unittest.cc

 // Copyright (c) 2012 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/workspace_window_resizer.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/display/mouse_cursor_event_filter.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_ash.h"
@@ skipping 56 matching lines @@
     UpdateDisplay(StringPrintf("800x%d", kRootHeight));
 
     aura::RootWindow* root = Shell::GetPrimaryRootWindow();
     gfx::Rect root_bounds(root->bounds());
     EXPECT_EQ(kRootHeight, root_bounds.height());
     EXPECT_EQ(800, root_bounds.width());
     Shell::GetInstance()->SetDisplayWorkAreaInsets(root, gfx::Insets());
     window_.reset(new aura::Window(&delegate_));
     window_->SetType(aura::client::WINDOW_TYPE_NORMAL);
     window_->Init(ui::LAYER_NOT_DRAWN);
-    window_->SetParent(NULL);
+    AddToRootWindow(window_.get());
     window_->set_id(1);
 
     window2_.reset(new aura::Window(&delegate2_));
     window2_->SetType(aura::client::WINDOW_TYPE_NORMAL);
     window2_->Init(ui::LAYER_NOT_DRAWN);
-    window2_->SetParent(NULL);
+    AddToRootWindow(window2_.get());
     window2_->set_id(2);
 
     window3_.reset(new aura::Window(&delegate3_));
     window3_->SetType(aura::client::WINDOW_TYPE_NORMAL);
     window3_->Init(ui::LAYER_NOT_DRAWN);
-    window3_->SetParent(NULL);
+    AddToRootWindow(window3_.get());
     window3_->set_id(3);
   }
 
   virtual void TearDown() OVERRIDE {
     window_.reset();
     window2_.reset();
     window3_.reset();
     AshTestBase::TearDown();
   }
 
@@ skipping 1360 matching lines @@
     // Move it 100 to the bottom.
     resizer->Drag(CalculateDragPoint(*resizer, 0, 100), 0);
     EXPECT_EQ("0,150 400x200", window_->bounds().ToString());
     resizer->CompleteDrag(0);
     EXPECT_TRUE(ash::wm::HasUserChangedWindowPositionOrSize(window_.get()));
   }
 }
 
 }  // namespace internal
 }  // namespace ash