Replace AllAppsTileItemView with ArrowExpandView

ui/app_list/views/expand_arrow_view.h

+// 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.
+
+#ifndef UI_APP_LIST_VIEWS_EXPAND_ARROW_VIEW_H_
+#define UI_APP_LIST_VIEWS_EXPAND_ARROW_VIEW_H_
+
+#include "ui/views/controls/button/button.h"
+#include "ui/views/controls/button/custom_button.h"
+
+namespace views {
+class ImageView;
+class InkDrop;
+class InkDropMask;
+class InkDropRipple;
+class InkDropHighlight;
+}  // namespace views
+
+namespace app_list {
+
+class AppListView;
+class ContentsView;
+
+// A tile item for the expand arrow on the start page.
+class ExpandArrowView : public views::CustomButton,
+                        public views::ButtonListener {
+ public:
+  ExpandArrowView(ContentsView* contents_view, AppListView* app_list_view);
+

[xiyuan, 2017/06/27 19:57:06]

nit: get rid of this empty line

[weidongg, 2017/06/27 20:41:48]

Done.

+  ~ExpandArrowView() override;
+
+  // Overridden from views::ButtonListener:
+  void ButtonPressed(views::Button* sender, const ui::Event& event) override;
+
+  // Overridden from views::View:
+  gfx::Size CalculatePreferredSize() const override;
+  void Layout() override;
+
+ protected:

[xiyuan, 2017/06/27 19:57:06]

I am okay to just make those below public.

[weidongg, 2017/06/27 20:41:50]

Done.

+  // Overridden from views::InkDropHost:
+  std::unique_ptr<views::InkDrop> CreateInkDrop() override;
+  std::unique_ptr<views::InkDropMask> CreateInkDropMask() const override;
+  std::unique_ptr<views::InkDropRipple> CreateInkDropRipple() const override;
+  std::unique_ptr<views::InkDropHighlight> CreateInkDropHighlight()
+      const override;
+
+ private:
+  ContentsView* contents_view_;

[xiyuan, 2017/06/27 19:57:06]

nit: This can be a const ptr too.
i.e.
  ContentsView* -> ContentsView* const

[weidongg, 2017/06/27 20:41:48]

Done.

+  AppListView* const app_list_view_;  // Owned by the views hierarchy.
+
+  views::ImageView* icon_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExpandArrowView);
+};
+
+}  // namespace app_list
+
+#endif  // UI_APP_LIST_VIEWS_EXPAND_ARROW_VIEW_H_