Add desktop engagement metrics.

chrome/browser/metrics/chrome_visibility_observer_browsertest.cc

+// Copyright (c) 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/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"
+
+class MockChromeVisibilityObserver : public metrics::ChromeVisibilityObserver {
+ public:
+  MockChromeVisibilityObserver() : is_active_(false) {}
+
+  bool IsActive() { return is_active_; }
+
+  static MockChromeVisibilityObserver* GetInstance() {
+    return base::Singleton<MockChromeVisibilityObserver>::get();
+  }
+
+  static void Initialize() { BrowserList::AddObserver(GetInstance()); }
+
+ 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::Initialize();
+  MockChromeVisibilityObserver* observer =
+      MockChromeVisibilityObserver::GetInstance();
+
+  EXPECT_FALSE(observer->IsActive());
+  Browser* new_browser = CreateBrowser(browser()->profile());
+  EXPECT_TRUE(observer->IsActive());
+
+  Browser* incognito_browser = CreateIncognitoBrowser();
+  EXPECT_TRUE(observer->IsActive());
+
+  CloseBrowserSynchronously(incognito_browser);
+  EXPECT_TRUE(observer->IsActive());
+
+  CloseBrowserSynchronously(new_browser);
+  CloseBrowserSynchronously(browser());
+  EXPECT_FALSE(observer->IsActive());
+}