Add rudimentary mash shelf functionality.

mash/shelf/shelf_view.h

Index: mash/shelf/shelf_view.h
diff --git a/mash/shelf/shelf_view.h b/mash/shelf/shelf_view.h
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+// Copyright 2015 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 MASH_SHELF_SHELF_VIEW_H_
+#define MASH_SHELF_SHELF_VIEW_H_
+
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "mash/wm/public/interfaces/user_window_controller.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
+#include "ui/views/controls/button/button.h"
+#include "ui/views/widget/widget_delegate.h"
+
+namespace mojo {
+class ApplicationImpl;
+}
+
+namespace views {
+class LabelButton;
+}
+
+namespace mash {
+namespace shelf {
+
+// A rudimentary mash shelf, used to build up the required wm interfaces.
+class ShelfView : public views::WidgetDelegateView,
+                  public views::ButtonListener,
+                  public mash::wm::mojom::UserWindowObserver {
+ public:
+  explicit ShelfView(mojo::ApplicationImpl* app);
+  ~ShelfView() override;
+
+ private:
+  // Overridden from views::View:
+  void OnPaint(gfx::Canvas* canvas) override;
+  gfx::Size GetPreferredSize() const override;
+
+  // Overridden from views::WidgetDelegate:
+  views::View* GetContentsView() override;
+
+  // Overridden from views::ButtonListener:
+  void ButtonPressed(views::Button* sender, const ui::Event& event) override;
+
+  // Overridden from mash::wm::mojom::UserWindowObserver:
+  void OnUserWindowObserverAdded(mojo::Array<uint32_t> window_ids) override;
+  void OnUserWindowAdded(uint32_t window_id) override;
+  void OnUserWindowRemoved(uint32_t window_id) override;
+
+  mojo::ApplicationImpl* app_;
+  std::vector<views::LabelButton*> open_window_buttons_;
+  mash::wm::mojom::UserWindowControllerPtr user_window_controller_;
+  mojo::Binding<mash::wm::mojom::UserWindowObserver> binding_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShelfView);
+};
+
+}  // namespace shelf
+}  // namespace mash
+
+#endif  // MASH_SHELF_SHELF_VIEW_H_