Add support code to test the cast system tray item.

ash/system/cast/tray_cast_testing_interface.h

+// 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_TESTING_INTERFACE_H_
+#define ASH_SYSTEM_CAST_TRAY_CAST_TESTING_INTERFACE_H_
+
+#include <string>
+
+#include "ash/ash_export.h"
+
+namespace ash {
+
+// The testing API for TrayCast.
+class ASH_EXPORT TrayCastTestingInterface {

[oshima, 2015/07/17 20:20:59]

We usually put the test API in ash/test, and make it friend so that the test API
class can access the internal state of the
target class. This way, you can avoid having test code / dependency in
production code. Please see

ash/test/*test_api.h

+ public:
+  virtual bool IsTrayInitializedForTest() const = 0;
+  virtual bool IsTrayVisibleForTest() const = 0;
+
+  // IsTrayCastViewVisibleForTest returns true if the active casting view is
+  // visible, ie, the TrayCast believes we are casting.
+  // IsTraySelectViewVisibleForTest returns true when the view for selecting a
+  // receiver is active, ie, the TrayCast believes we are not casting.
+  virtual bool IsTrayCastViewVisibleForTest() const = 0;
+  virtual bool IsTraySelectViewVisibleForTest() const = 0;
+
+  // Start a new cast to the given receiver.
+  virtual void StartCastForTest(const std::string& receiver_id) = 0;
+  virtual void StopCastForTest() = 0;
+
+  // 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.
+  virtual void OnCastingSessionStartedOrStopped(bool is_casting) = 0;
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_CAST_TRAY_CAST_TESTING_INTERFACE_H_