[sync] "TwoClientBookmarksSyncTest.Sanity" is flaky

chrome/browser/sync/test/integration/single_client_sessions_sync_test.cc

 // Copyright 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.
 
 #include "base/macros.h"
 #include "base/test/histogram_tester.h"
 #include "chrome/browser/sessions/session_service.h"
 #include "chrome/browser/sync/test/integration/profile_sync_service_harness.h"
 #include "chrome/browser/sync/test/integration/sessions_helper.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
 #include "chrome/browser/sync/test/integration/typed_urls_helper.h"
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "components/browser_sync/profile_sync_service.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/sessions/core/session_types.h"
 #include "components/sync/base/time.h"
+#include "components/sync/driver/sync_driver_switches.h"
 #include "components/sync/test/fake_server/fake_server_verifier.h"
 #include "components/sync/test/fake_server/sessions_hierarchy.h"
 
 using fake_server::SessionsHierarchy;
 using sessions_helper::CheckInitialState;
 using sessions_helper::GetLocalWindows;
 using sessions_helper::GetSessionData;
 using sessions_helper::ModelAssociatorHasTabWithUrl;
 using sessions_helper::OpenTabAndGetLocalWindows;
 using sessions_helper::ScopedWindowMap;
 using sessions_helper::SessionWindowMap;
 using sessions_helper::SyncedSessionVector;
 using sessions_helper::WaitForTabsToLoad;
 using sessions_helper::WindowsMatch;
 using typed_urls_helper::GetUrlFromClient;
 
 class SingleClientSessionsSyncTest : public SyncTest {
  public:
   SingleClientSessionsSyncTest() : SyncTest(SINGLE_CLIENT) {}
   ~SingleClientSessionsSyncTest() override {}
 
+  void SetUpCommandLine(base::CommandLine* cl) override {
+    // This is a hacky override of the switches set in
+    // SyncTest::SetUpCommandLine() to avoid the switch that speeds up nudge
+    // delays. CookieJarMismatch asserts exact histogram counts assuming that

[Nicolas Zea, 2016/11/09 00:35:13]

Hmm, what's the issue with CookieJarMismatch? Ideally it shouldn't depend on
slow syncs.

[Patrick Noland, 2016/11/10 22:13:00]

SessionsHelper waits for a title to load before deciding a tab is loaded when
calling OpenTabAndGetLocalWindows. SessionsSyncManager doesn't care if the title
is present or not, so it can plausibly commit the title-less tab, trigering the
histogram logic, then commit again once the title shows up. 

+    // sync is (relatively) slow, so we preserve that assumption.
+    if (!cl->HasSwitch(switches::kDisableBackgroundNetworking))
+      cl->AppendSwitch(switches::kDisableBackgroundNetworking);
+
+    if (!cl->HasSwitch(switches::kSyncShortInitialRetryOverride))
+      cl->AppendSwitch(switches::kSyncShortInitialRetryOverride);
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(SingleClientSessionsSyncTest);
 };
 
 IN_PROC_BROWSER_TEST_F(SingleClientSessionsSyncTest, Sanity) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
 
   ASSERT_TRUE(CheckInitialState(0));
 
   // Add a new session to client 0 and wait for it to sync.
@@ skipping 143 matching lines @@
   // Verify the cookie jar mismatch bool is set to false.
   ASSERT_TRUE(GetFakeServer()->GetLastCommitMessage(&message));
   ASSERT_FALSE(message.commit().config_params().cookie_jar_mismatch());
 
   // Verify the histograms were recorded properly.
   histogram_tester.ExpectTotalCount("Sync.CookieJarMatchOnNavigation", 2);
   histogram_tester.ExpectBucketCount("Sync.CookieJarMatchOnNavigation", true,
                                      1);
   histogram_tester.ExpectUniqueSample("Sync.CookieJarEmptyOnMismatch", true, 1);
 }