WIP: Eliminate event.target() usage from TrayEventFilter

ash/container_delegate_aura.h

Index: ash/container_delegate_aura.h
diff --git a/ash/container_delegate_aura.h b/ash/container_delegate_aura.h
new file mode 100644
index 0000000000000000000000000000000000000000..a23845c74ce47df15f11a854c95536622e026db0
--- /dev/null
+++ b/ash/container_delegate_aura.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_CONTAINER_DELEGATE_AURA_H_
+#define ASH_CONTAINER_DELEGATE_AURA_H_
+
+#include "ash/ash_export.h"
+#include "ash/container_delegate.h"
+#include "base/macros.h"
+
+namespace views {
+class Widget;
+}
+
+namespace ash {
+
+// The ash::ContainerDelegate implementation for classic ash.
+class ASH_EXPORT ContainerDelegateAura : public ContainerDelegate {
+ public:
+  ContainerDelegateAura();
+  ~ContainerDelegateAura() override;
+
+  // ContainerDelegate:
+  bool IsInMenuContainer(views::Widget* widget) override;
+  bool IsInStatusContainer(views::Widget* widget) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ContainerDelegateAura);
+};
+
+}  // namespace ash
+
+#endif  // ASH_CONTAINER_DELEGATE_AURA_H_