Makes workspace 2 show an alternate background (system background)

ash/wm/workspace/workspace_manager2.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_manager2.h"
 
 #include <algorithm>
 #include <functional>
 
 #include "ash/ash_switches.h"
 #include "ash/screen_ash.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/base_layout_manager.h"
 #include "ash/wm/property_util.h"
 #include "ash/wm/shelf_layout_manager.h"
 #include "ash/wm/window_animations.h"
 #include "ash/wm/window_properties.h"
 #include "ash/wm/window_util.h"
+#include "ash/wm/workspace/system_background_controller.h"
 #include "ash/wm/workspace/workspace_layout_manager2.h"
 #include "ash/wm/workspace/workspace2.h"
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/stringprintf.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/env.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
@@ skipping 227 matching lines @@
     if (FindWorkspace(workspace) == workspaces_.end()) {
       contents_view_->StackChildAbove(workspace->window(),
                                       workspaces_.back()->window());
       workspaces_.push_back(workspace);
     }
   }
 
   Workspace2* last_active = active_workspace_;
   active_workspace_ = workspace;
 
+  destroy_background_timer_.Stop();
+  if (active_workspace_ == desktop_workspace()) {
+    destroy_background_timer_.Start(
+        FROM_HERE, GetSystemBackgroundDestroyDuration(),
+        this, &WorkspaceManager2::DestroySystemBackground);
+  } else if (!background_controller_.get()) {
+    background_controller_.reset(new SystemBackgroundController(
+                                     contents_view_->GetRootWindow()));
+  }
+
   UpdateShelfVisibility();
 
   if (animate_type != ANIMATE_NONE) {
     AnimateBetweenWorkspaces(last_active->window(), workspace->window(),
                              (animate_type == ANIMATE_OLD_AND_NEW));
   }
 
   RootWindowController* root_controller = GetRootWindowController(
       contents_view_->GetRootWindow());
   if (root_controller) {
@@ skipping 83 matching lines @@
     SetActiveWorkspace(*(workspace_i - 1), animate_type);
 }
 
 void WorkspaceManager2::ScheduleDelete(Workspace2* workspace) {
   to_delete_.insert(workspace);
   delete_timer_.Stop();
   delete_timer_.Start(FROM_HERE, base::TimeDelta::FromSeconds(1), this,
                       &WorkspaceManager2::ProcessDeletion);
 }
 
+void WorkspaceManager2::DestroySystemBackground() {
+  background_controller_.reset();
+}
+
 void WorkspaceManager2::ProcessDeletion() {
   std::set<Workspace2*> to_delete;
   to_delete.swap(to_delete_);
   for (std::set<Workspace2*>::iterator i = to_delete.begin();
        i != to_delete.end(); ++i) {
     Workspace2* workspace = *i;
     if (workspace->window()->layer()->children().empty()) {
       delete workspace->ReleaseWindow();
       delete workspace;
     } else {
@@ skipping 87 matching lines @@
           child, old_layer);
     } else {
       DCHECK(!old_layer);
     }
   }
   UpdateShelfVisibility();
 }
 
 }  // namespace internal
 }  // namespace ash