VR: Factor transient timing out of UiSceneManager.

chrome/browser/android/vr_shell/ui_elements/transience_manager_unittest.cc

+// Copyright 2017 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.
+
+#include "chrome/browser/android/vr_shell/ui_elements/transience_manager.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
+#include "base/test/scoped_mock_time_message_loop_task_runner.h"
+#include "chrome/browser/android/vr_shell/ui_elements/ui_element.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace vr_shell {
+
+TEST(TransienceManager, Works) {
+  base::MessageLoop message_loop_;
+  base::ScopedMockTimeMessageLoopTaskRunner task_runner_;
+
+  UiElement element;
+
+  TransienceManager transience(&element, base::TimeDelta::FromSeconds(10));
+  EXPECT_EQ(element.visible(), false);
+
+  transience.KickVisibility();
+  EXPECT_EQ(element.visible(), false);
+
+  transience.SetEnabled(true);
+  EXPECT_EQ(element.visible(), false);
+
+  // Kick visibility, and make sure the element appears transiently.
+  transience.KickVisibility();
+  EXPECT_EQ(element.visible(), true);
+  task_runner_->FastForwardUntilNoTasksRemain();
+  EXPECT_EQ(element.visible(), false);
+
+  transience.KickVisibility();
+  EXPECT_EQ(element.visible(), true);
+  transience.SetEnabled(false);
+  EXPECT_EQ(element.visible(), false);
+  transience.SetEnabled(true);
+  EXPECT_EQ(element.visible(), false);
+}
+
+}  // namespace vr_shell