Add UI for cast system tray integration

ash/system/cast/tray_cast.h

Index: ash/system/cast/tray_cast.h
diff --git a/ash/system/cast/tray_cast.h b/ash/system/cast/tray_cast.h
new file mode 100644
index 0000000000000000000000000000000000000000..059c168e6c795649b268d6493e291a76aa95856d
--- /dev/null
+++ b/ash/system/cast/tray_cast.h
@@ -0,0 +1,61 @@
+// 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 ASH_SYSTEM_CAST_TRAY_CAST_H_
+#define ASH_SYSTEM_CAST_TRAY_CAST_H_
+
+#include "ash/shell_observer.h"
+#include "ash/system/tray/system_tray_item.h"
+
+namespace ash {
+namespace tray {
+class CastTrayView;
+class CastSelectDefaultView;
+class CastDetailedView;
+class CastDuplexView;
+}  // namespace tray
+
+class CastConfigDelegate;
+
+class TrayCast : public SystemTrayItem, public ShellObserver {
+ public:
+  explicit TrayCast(SystemTray* system_tray);
+  ~TrayCast() override;
+
+ private:
+  bool HasCastExtension();
+
+  // Overridden from SystemTrayItem.
+  views::View* CreateTrayView(user::LoginStatus status) override;
+  views::View* CreateDefaultView(user::LoginStatus status) override;
+  views::View* CreateDetailedView(user::LoginStatus status) override;
+  void DestroyTrayView() override;
+  void DestroyDefaultView() override;
+  void DestroyDetailedView() override;
+  void UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) override;
+
+  // Overridden from ShellObserver.
+  void OnCastingSessionStartedOrStopped(bool started) override;
+
+  // This makes sure that the current view displayed in the tray is the correct
+  // one, depending on if we are currently casting. If we're casting, then a
+  // view with a stop button is displayed; otherwise, a view that links to a
+  // detail view is displayed instead that allows the user to easily begin a
+  // casting session.
+  void UpdatePrimaryView();
+
+  bool is_casting_ = false;
+
+  // Not owned.
+  tray::CastTrayView* tray_ = nullptr;
+  tray::CastDuplexView* default_ = nullptr;
+  tray::CastDetailedView* detailed_ = nullptr;
+  CastConfigDelegate* cast_config_delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrayCast);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_CAST_TRAY_CAST_H_