Add WorkspaceObserver to observe changes in workspace state

ui/aura_shell/show_state_controller.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/show_state_controller.h"
 
 #include "ui/aura/aura_constants.h"
 #include "ui/aura/window.h"
-#include "ui/aura_shell/default_container_layout_manager.h"
 #include "ui/aura_shell/property_util.h"
 #include "ui/aura_shell/workspace/workspace.h"
 #include "ui/aura_shell/workspace/workspace_manager.h"
 #include "ui/base/ui_base_types.h"
 
 namespace aura_shell {
 namespace internal {
 
 ShowStateController::ShowStateController(
-    DefaultContainerLayoutManager* layout_manager)
-    : layout_manager_(layout_manager) {
+    WorkspaceManager* workspace_manager)
+    : workspace_manager_(workspace_manager) {
 }
 
 ShowStateController::~ShowStateController() {
 }
 
 void ShowStateController::OnPropertyChanged(aura::Window* window,
                                             const char* name,
                                             void* old) {
   if (name != aura::kShowStateKey)
     return;
   if (window->GetIntProperty(name) == ui::SHOW_STATE_NORMAL) {
     // Restore the size of window first, then let Workspace layout the window.
     const gfx::Rect* restore = GetRestoreBounds(window);
     window->SetProperty(aura::kRestoreBoundsKey, NULL);
     if (restore)
       window->SetBounds(*restore);
     delete restore;
   } else if (old == reinterpret_cast<void*>(ui::SHOW_STATE_NORMAL)) {
     // Store the restore bounds only if previous state is normal.
     DCHECK(window->GetProperty(aura::kRestoreBoundsKey) == NULL);
     SetRestoreBounds(window, window->GetTargetBounds());
   }
 
-  layout_manager_->set_ignore_calculate_bounds(true);
-  layout_manager_->workspace_manager()->FindBy(window)->Layout(NULL, window);
-  layout_manager_->set_ignore_calculate_bounds(false);
+  workspace_manager_->FindBy(window)->Layout(NULL, window);
 }
 
 }  // namespace internal
 }  // namespace aura_shell