[DesktopSessionDurationTracker] Remove visibility-switch timeout from session length.

chrome/browser/metrics/desktop_session_duration/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_session_duration/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; }
+  void SendVisibilityChangeEvent(bool active,
+                                 base::TimeDelta time_ago) 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());
 }