Wait visibility changes with RunLoop.

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 "base/run_loop.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) {}
+  MockChromeVisibilityObserver() : is_active_(false) {
+    ResetRunLoop();
+  }
+
+  void Wait() {
+    run_loop_->Run();
+  }
+
+  void ResetRunLoop() {
+    run_loop_.reset(new base::RunLoop());
+  }
 
   bool is_active() const { return is_active_; }
+  void set_is_active(bool is_active) { is_active_ = is_active; }
 
  private:
   void SendVisibilityChangeEvent(bool active,
                                  base::TimeDelta time_ago) override {
     is_active_ = active;
+    // In this test browser became inactive after browser is removed, thus
+    // in this case quit runloop in OnBrowserRemoved().
+    if (is_active_)
+      run_loop_->Quit();
+  }
+
+  void OnBrowserRemoved(Browser* browser) override {
+    metrics::ChromeVisibilityObserver::OnBrowserRemoved(browser);
+    run_loop_->Quit();
   }
 
   bool is_active_;
+  std::unique_ptr<base::RunLoop> run_loop_;
 
   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());
+  observer.Wait();
   EXPECT_TRUE(observer.is_active());
 
+  observer.ResetRunLoop();
+  observer.set_is_active(false);
   Browser* incognito_browser = CreateIncognitoBrowser();
+  observer.Wait();
   EXPECT_TRUE(observer.is_active());
 
+  observer.ResetRunLoop();
   CloseBrowserSynchronously(incognito_browser);
+  observer.Wait();
   EXPECT_TRUE(observer.is_active());
 
+  observer.ResetRunLoop();
   CloseBrowserSynchronously(new_browser);
+  observer.Wait();
+  EXPECT_TRUE(observer.is_active());
+
+  observer.ResetRunLoop();
   CloseBrowserSynchronously(browser());
+  observer.Wait();
   EXPECT_FALSE(observer.is_active());
 }