Fix flakiness in MetricsServiceTest.CrashRenderers

chrome/browser/metrics/metrics_service_browsertest.cc

 // Copyright (c) 2012 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.
 
 // Tests the MetricsService stat recording to make sure that the numbers are
 // what we expect.
 
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 56 matching lines @@
   EXPECT_EQ(4, prefs->GetInteger(prefs::kStabilityPageLoadCount));
 #else
   EXPECT_EQ(3, prefs->GetInteger(prefs::kStabilityPageLoadCount));
 #endif
   EXPECT_EQ(0, prefs->GetInteger(prefs::kStabilityRendererCrashCount));
   // TODO(isherman): We should also verify that prefs::kStabilityExitedCleanly
   // is set to true, but this preference isn't set until the browser
   // exits... it's not clear to me how to test that.
 }
 
-// Flaky: http://crbug.com/18738
-IN_PROC_BROWSER_TEST_F(MetricsServiceTest, FLAKY_CrashRenderers) {
+IN_PROC_BROWSER_TEST_F(MetricsServiceTest, CrashRenderers) {
   OpenTabs();
 
   // Kill the process for one of the tabs.
   ui_test_utils::WindowedNotificationObserver observer(
       content::NOTIFICATION_RENDERER_PROCESS_CLOSED,
       content::NotificationService::AllSources());
   ui_test_utils::NavigateToURL(browser(), GURL(chrome::kChromeUICrashURL));
   observer.Wait();
 
+  // The MetricsService listens for the same notification, so the |observer|
+  // might finish waiting before the MetricsService has a chance to process the
+  // notification.  To avoid racing here, we repeatedly run the message loop
+  // until the MetricsService catches up.  This should happen "real soon now",
+  // since the notification is posted to all observers essentially
+  // simultaneously... so busy waiting here shouldn't be too bad.
+  const PrefService* prefs = g_browser_process->local_state();
+  while (!prefs->GetInteger(prefs::kStabilityRendererCrashCount)) {
+    ui_test_utils::RunAllPendingInMessageLoop();
+  }
+
   // Verify that the expected stability metrics were recorded.
-  const PrefService* prefs = g_browser_process->local_state();
   EXPECT_EQ(1, prefs->GetInteger(prefs::kStabilityLaunchCount));
 #if defined(USE_VIRTUAL_KEYBOARD)
   // The keyboard page loads.
   EXPECT_EQ(5, prefs->GetInteger(prefs::kStabilityPageLoadCount));
 #else
   EXPECT_EQ(4, prefs->GetInteger(prefs::kStabilityPageLoadCount));
 #endif
   EXPECT_EQ(1, prefs->GetInteger(prefs::kStabilityRendererCrashCount));
   // TODO(isherman): We should also verify that prefs::kStabilityExitedCleanly
   // is set to true, but this preference isn't set until the browser
   // exits... it's not clear to me how to test that.
 }