Rename DesktopEngagement* to DesktopSessionDuration*.

chrome/browser/metrics/desktop_engagement/chrome_visibility_observer_browsertest.cc

-// 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.
-
-#include "chrome/browser/metrics/desktop_engagement/chrome_visibility_observer.h"
-
-#include "base/memory/singleton.h"
-#include "chrome/browser/chrome_notification_types.h"
-#include "chrome/browser/ui/browser.h"
-#include "chrome/browser/ui/browser_list.h"
-#include "chrome/test/base/in_process_browser_test.h"
-#include "chrome/test/base/ui_test_utils.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/test/test_utils.h"
-
-// Mock class for |ChromeVisibilityObserver| for testing.
-class MockChromeVisibilityObserver : public metrics::ChromeVisibilityObserver {
- public:
-  MockChromeVisibilityObserver() : is_active_(false) {}
-
-  bool is_active() const { return is_active_; }
-
- private:
-  void SendVisibilityChangeEvent(bool active) override { is_active_ = active; }
-
-  bool is_active_;
-
-  DISALLOW_COPY_AND_ASSIGN(MockChromeVisibilityObserver);
-};
-
-class ChromeVisibilityObserverBrowserTest : public InProcessBrowserTest {};
-
-IN_PROC_BROWSER_TEST_F(ChromeVisibilityObserverBrowserTest, VisibilityTest) {
-  MockChromeVisibilityObserver observer;
-
-  EXPECT_FALSE(observer.is_active());
-  Browser* new_browser = CreateBrowser(browser()->profile());
-  EXPECT_TRUE(observer.is_active());
-
-  Browser* incognito_browser = CreateIncognitoBrowser();
-  EXPECT_TRUE(observer.is_active());
-
-  CloseBrowserSynchronously(incognito_browser);
-  EXPECT_TRUE(observer.is_active());
-
-  CloseBrowserSynchronously(new_browser);
-  CloseBrowserSynchronously(browser());
-  EXPECT_FALSE(observer.is_active());
-}