Moves ToastManager from Shell to WmShell

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 4750b3fe201c3664fdb0cad756625a616819b739..55b0da9ac478cd28fc607be6134c9ea81164df72 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -28,7 +28,6 @@
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/system/locale/locale_notification_controller.h"
 #include "ash/common/system/status_area_widget.h"
-#include "ash/common/system/toast/toast_manager.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_window_manager.h"
@@ -676,7 +675,7 @@ Shell::~Shell() {
   DeactivateKeyboard();
 
   // Destroy toasts
-  toast_manager_.reset();
+  wm_shell_->DeleteToastManager();
 
   // Destroy SystemTrayDelegate before destroying the status area(s). Make sure
   // to deinitialize the shelf first, as it is initialized after the delegate.
@@ -1027,9 +1026,6 @@ void Shell::Init(const ShellInitParams& init_params) {
 
   locale_notification_controller_.reset(new LocaleNotificationController);
 
-  // Initialize toast manager
-  toast_manager_.reset(new ToastManager);
-
 #if defined(OS_CHROMEOS)
   // Create TouchTransformerController before
   // WindowTreeHostManager::InitDisplays()