Add support code to test the cast system tray item.

ash/test/tray_cast_test_api.h

Index: ash/test/tray_cast_test_api.h
diff --git a/ash/test/tray_cast_test_api.h b/ash/test/tray_cast_test_api.h
new file mode 100644
index 0000000000000000000000000000000000000000..46653f72461b40b2cbb713640c25c454f6a5b5fc
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+++ b/ash/test/tray_cast_test_api.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 ASH_TEST_TRAY_CAST_TEST_API_H_
+#define ASH_TEST_TRAY_CAST_TEST_API_H_
+
+#include <string>
+
+#include "ash/ash_export.h"
+#include "ash/system/cast/tray_cast.h"
+
+namespace ash {
+
+class ASH_EXPORT TrayCastTestAPI {
+ public:
+  explicit TrayCastTestAPI(TrayCast* tray_cast);
+  ~TrayCastTestAPI();
+
+  bool IsTrayInitialized() const;
+  bool IsTrayVisible() const;
+
+  // IsTrayCastViewVisible returns true if the active casting view is
+  // visible, ie, the TrayCast believes we are casting.
+  // IsTraySelectViewVisible returns true when the view for selecting a
+  // receiver is active, ie, the TrayCast believes we are not casting.
+  bool IsTrayCastViewVisible() const;
+  bool IsTraySelectViewVisible() const;
+
+  // Start a new cast to the given receiver.
+  void StartCast(const std::string& receiver_id);
+  void StopCast();
+
+  // Exposed callback to update the casting state. The test code needs to call
+  // this function manually, as there is no actual casting going on. In a real
+  // environment, this method is invoked by the casting system in Chrome.
+  void OnCastingSessionStartedOrStopped(bool is_casting);
+
+ private:
+  bool IsViewDrawn(TrayCast::ChildViewId id) const;
+
+  // Not owned.
+  TrayCast* tray_cast_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrayCastTestAPI);
+};
+
+}  // namespace ash
+
+#endif  // ASH_TEST_TRAY_CAST_TEST_API_H_