mash: Support ShelfModel access in Chrome.

ash/public/cpp/remote_shelf_item_delegate.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 ASH_PUBLIC_CPP_REMOTE_SHELF_ITEM_DELEGATE_H_
+#define ASH_PUBLIC_CPP_REMOTE_SHELF_ITEM_DELEGATE_H_
+
+#include "ash/public/cpp/shelf_item_delegate.h"
+
+namespace ash {
+
+// A ShelfItemDelegate that forwards calls to a remote ShelfItemDelegatePtr.
+// Used by Ash and Chrome ShelfModels for delegation across service boundaries.
+class ASH_PUBLIC_EXPORT RemoteShelfItemDelegate : public ShelfItemDelegate {

[Tom Sepez, 2017/05/31 21:14:27]

This is WM -> browser or other trusted components, right?

[msw, 2017/05/31 21:36:54]

Yes, this is WM <-> browser only for now. Ash constructs these when Chrome calls
[ash::mojom::]ShelfController::SetShelfItemDelegate, and Chrome constructs these
when Ash calls
[ash::mojom::ShelfObserver|ChromeLauncherController]::OnShelfItemDelegateChanged(),
as per Chrome's use of [ash::mojom::]ShelfController::AddObserver(). This CL
should not allow any other components to connect to either interface, no less
inject their own ShelfItemDelegates.

+ public:
+  RemoteShelfItemDelegate(const ShelfID& shelf_id,
+                          mojom::ShelfItemDelegatePtr delegate);
+  ~RemoteShelfItemDelegate() override;
+
+  // mojom::ShelfItemDelegate
+  void ItemSelected(std::unique_ptr<ui::Event> event,
+                    int64_t display_id,
+                    ShelfLaunchSource source,
+                    ItemSelectedCallback callback) override;
+  void ExecuteCommand(uint32_t command_id, int32_t event_flags) override;
+  void Close() override;
+
+ private:
+  // The pointer to the remote delegate.
+  mojom::ShelfItemDelegatePtr delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemoteShelfItemDelegate);
+};
+
+}  // namespace ash
+
+#endif  // ASH_PUBLIC_CPP_REMOTE_SHELF_ITEM_DELEGATE_H_