[Aura] Support always-on-top top level window.

ui/aura_shell/shell.cc

 // Copyright (c) 2011 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 "ui/aura_shell/shell.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "ui/aura/aura_switches.h"
 #include "ui/aura/desktop.h"
 #include "ui/aura/toplevel_window_container.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_types.h"
+#include "ui/aura_shell/always_on_top_controller.h"
 #include "ui/aura_shell/default_container_event_filter.h"
 #include "ui/aura_shell/default_container_layout_manager.h"
 #include "ui/aura_shell/desktop_layout_manager.h"
 #include "ui/aura_shell/launcher/launcher.h"
 #include "ui/aura_shell/shelf_layout_controller.h"
 #include "ui/aura_shell/shell_delegate.h"
 #include "ui/aura_shell/shell_factory.h"
 #include "ui/aura_shell/shell_window_ids.h"
 #include "ui/aura_shell/toplevel_layout_manager.h"
 #include "ui/aura_shell/workspace/workspace_controller.h"
@@ skipping 51 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // Shell, public:
 
 Shell::Shell()
     : ALLOW_THIS_IN_INITIALIZER_LIST(method_factory_(this)) {
   aura::Desktop::GetInstance()->SetDelegate(this);
 }
 
 Shell::~Shell() {
+  DCHECK(instance_ == this);
+  instance_ = NULL;
 }
 
 // static
 Shell* Shell::GetInstance() {
   if (!instance_) {
     instance_ = new Shell;
     instance_->Init();
   }
   return instance_;
 }
 
 void Shell::Init() {
   aura::Desktop* desktop_window = aura::Desktop::GetInstance();
   desktop_window->SetCursor(aura::kCursorPointer);
 
   aura::Window::Windows containers;
   CreateSpecialContainers(&containers);
   aura::Window::Windows::const_iterator i;
   for (i = containers.begin(); i != containers.end(); ++i) {
     (*i)->Init(ui::Layer::LAYER_HAS_NO_TEXTURE);
     desktop_window->AddChild(*i);
     (*i)->Show();
   }
 
+  always_on_top_controller_.reset(new internal::AlwaysOnTopController);
+  always_on_top_controller_->SetContainers(
+    GetContainer(internal::kShellWindowId_DefaultContainer),

[Ben Goodger (Google), 2011/11/09 17:18:09]

nit: 4-space indent

[xiyuan, 2011/11/09 17:42:18]

Done.

+    GetContainer(internal::kShellWindowId_AlwaysOnTopContainer));
+
   internal::DesktopLayoutManager* desktop_layout =
       new internal::DesktopLayoutManager(desktop_window);
   desktop_window->SetLayoutManager(desktop_layout);
 
   desktop_layout->set_background_widget(internal::CreateDesktopBackground());
   aura::ToplevelWindowContainer* toplevel_container =
       GetContainer(internal::kShellWindowId_DefaultContainer)->
           AsToplevelWindowContainer();
   launcher_.reset(new Launcher(toplevel_container));
 
@@ skipping 49 matching lines @@
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Shell, aura::DesktopDelegate implementation:
 
 void Shell::AddChildToDefaultParent(aura::Window* window) {
   aura::Window* parent = NULL;
   switch (window->type()) {
     case aura::WINDOW_TYPE_NORMAL:
     case aura::WINDOW_TYPE_POPUP:
-      parent = GetContainer(internal::kShellWindowId_DefaultContainer);
+      parent = always_on_top_controller_->GetContainer(window);
       break;
     case aura::WINDOW_TYPE_MENU:
     case aura::WINDOW_TYPE_TOOLTIP:
       parent = GetContainer(internal::kShellWindowId_MenusAndTooltipsContainer);
       break;
     default:
       NOTREACHED() << "Window " << window->id()
                    << " has unhandled type " << window->type();
       break;
   }
   parent->AddChild(window);
 }
 
 aura::Window* Shell::GetTopmostWindowToActivate(aura::Window* ignore) const {
   const aura::ToplevelWindowContainer* container =
       GetContainer(internal::kShellWindowId_DefaultContainer)->
           AsToplevelWindowContainer();
   return container->GetTopmostWindowToActivate(ignore);
 }
 
 }  // namespace aura_shell