Ash: Implement Toasts

ash/system/toast/toast_manager.h

Index: ash/system/toast/toast_manager.h
diff --git a/ash/system/toast/toast_manager.h b/ash/system/toast/toast_manager.h
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index 0000000000000000000000000000000000000000..058f412902bf41e23c2de50d3c08fb9f56a118ec
--- /dev/null
+++ b/ash/system/toast/toast_manager.h
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+// Copyright 2016 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_SYSTEM_TOAST_TOAST_MANAGER_H_
+#define ASH_SYSTEM_TOAST_TOAST_MANAGER_H_
+
+#include <queue>
+#include <string>
+
+#include "ash/ash_export.h"
+#include "ash/shell_observer.h"
+#include "ash/system/toast/toast_overlay.h"
+#include "base/memory/singleton.h"
+#include "base/threading/thread_checker.h"
+
+namespace ash {
+
+// Class managing toast requests.
+class ASH_EXPORT ToastManager : public ToastOverlay::Delegate {
+ public:
+  ToastManager();
+  ~ToastManager() override;
+
+  // Show a toast. If there are queued toasts, succeeding toasts are queued as
+  // well, and are shown one by one.
+  void Show(const std::string& text, uint64_t duration_ms);
+
+  // ToastOverlay::Delegate overrides:
+  void OnClosed() override;
+
+ private:
+  friend class ToastManagerTest;
+
+  void ShowLatest();
+  void OnDurationPassed(int toast_id);
+
+  int toast_id_for_testing() const { return toast_id_; }
+  ToastOverlay* GetCurrentOverlayForTesting() { return overlay_.get(); }
+  void ResetToastIdForTesting() { toast_id_ = 0; }
+
+  int toast_id_ = 0;
+  std::queue<std::pair<std::string, uint64_t>> queue_;
+  scoped_ptr<ToastOverlay> overlay_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(ToastManager);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_TOAST_TOAST_MANAGER_H_