mash: Create and show a shelf in mash.

ash/root_window_controller.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/root_window_controller.h"
 
 #include <queue>
 #include <vector>
 
 #include "ash/aura/aura_layout_manager_adapter.h"
@@ skipping 557 matching lines @@
   if (docked_layout_manager_) {
     docked_layout_manager_->Shutdown();
     docked_layout_manager_ = NULL;
   }
   aura::Window* root_window = GetRootWindow();
   aura::client::SetDragDropClient(root_window, NULL);
 
   if (shelf_widget_)
     shelf_widget_->Shutdown();
 
-  wm_shelf_aura_->Shutdown();
-
   // Close background widget first as it depends on tooltip.
   wallpaper_controller_.reset();
   animating_wallpaper_controller_.reset();
 
   workspace_controller_.reset();
   aura::client::SetTooltipClient(root_window, NULL);
 
   // Explicitly destroy top level windows. We do this as during part of
   // destruction such windows may query the RootWindow for state.
   aura::WindowTracker non_toplevel_windows;
@@ skipping 19 matching lines @@
   while (!root_window->children().empty()) {
     aura::Window* window = root_window->children()[0];
     if (window->owned_by_parent()) {
       delete window;
     } else {
       root_window->RemoveChild(window);
     }
   }
 
   shelf_widget_.reset();
+  // CloseChildWindows may be called twice during the shutdown of ash unittests.
+  // Avoid notifying WmShelf that the Shelf instance has been destroyed twice.
+  if (wm_shelf_aura_->shelf())
+    wm_shelf_aura_->ClearShelf();
   shelf_.reset();
 }
 
 void RootWindowController::MoveWindowsTo(aura::Window* dst) {
   // Clear the workspace controller, so it doesn't incorrectly update the shelf.
   workspace_controller_.reset();
   ReparentAllWindows(GetRootWindow(), dst);
 }
 
 ShelfLayoutManager* RootWindowController::GetShelfLayoutManager() {
@@ skipping 328 matching lines @@
     aura::Window* primary_root_window = Shell::GetInstance()
                                             ->window_tree_host_manager()
                                             ->GetPrimaryRootWindow();
     return GetRootWindowSettings(primary_root_window)->controller;
   }
 
   return GetRootWindowSettings(root_window)->controller;
 }
 
 }  // namespace ash