Draggable peeking/fullscreen launcher with transparent background.

ash/app_list/app_list_delegate_impl.cc

 // Copyright 2017 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/app_list/app_list_delegate_impl.h"
 
 #include "ash/root_window_controller.h"
-#include "ash/shelf/app_list_button.h"
-#include "ash/shelf/shelf.h"
-#include "ash/shelf/shelf_widget.h"
 #include "ash/shell.h"
 #include "ash/shell_port.h"
+#include "ui/app_list/app_list_features.h"
 #include "ui/app_list/presenter/app_list.h"
 
 namespace ash {
-
+// TODO(newcomer): Remove this class as a part of crbug.com/726838
 AppListDelegateImpl::AppListDelegateImpl() {
   Shell::Get()->app_list()->set_delegate(this);
 }
 
 AppListDelegateImpl::~AppListDelegateImpl() {
   Shell::Get()->app_list()->set_delegate(nullptr);
 }
 
 void AppListDelegateImpl::OnAppListVisibilityChanged(bool visible,
                                                      int64_t display_id) {
-  aura::Window* root_window =
-      ShellPort::Get()->GetRootWindowForDisplayId(display_id);
-  AppListButton* app_list_button =
-      Shelf::ForWindow(root_window)->shelf_widget()->GetAppListButton();
-  if (!app_list_button)
-    return;
-
-  if (visible)
-    app_list_button->OnAppListShown();
-  else
-    app_list_button->OnAppListDismissed();
+  if (app_list::features::IsFullscreenAppListEnabled()) {
+    aura::Window* root_window =
+        ShellPort::Get()->GetRootWindowForDisplayId(display_id);
+    Shell::Get()->OnAppListVisibilityChanged(visible, root_window);
+  }
 }
 
 }  // namespace ash