[Aura] Implement views-based applist.

ui/aura_shell/app_list/app_list_view_delegate.h

+// 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.
+
+#ifndef UI_AURA_SHELL_APP_LIST_APP_LIST_VIEW_DELEGATE_H_
+#define UI_AURA_SHELL_APP_LIST_APP_LIST_VIEW_DELEGATE_H_
+#pragma once
+
+#include "ui/aura_shell/aura_shell_export.h"
+
+namespace aura_shell {
+
+class AppListItemModel;
+
+class AURA_SHELL_EXPORT AppListViewDelegate {
+ public:
+  // AppListView owns the delegate.
+  virtual ~AppListViewDelegate() {}
+
+  // Invoked an AppListeItemModelView is  activated by click or enter key.
+  virtual void OnAppListItemActivated(AppListItemModel* item,
+                                      int event_flags) = 0;
+};
+
+}  // namespace aura_shell
+
+#endif  // UI_AURA_SHELL_APP_LIST_APP_LIST_VIEW_DELEGATE_H_