[Sync] Replacing NULL with nullptr/null throughout sync code.

chrome/browser/sync/sync_ui_util_unittest.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.
 
 #include <stddef.h>
 
 #include <memory>
 
 #include <set>
 #include "base/macros.h"
@@ skipping 172 matching lines @@
 // tests are unaffected, but STATUS_CASE_AUTHENTICATING can't exist in both
 // versions, so it we will require two separate tests, one using SigninManager
 // and one using SigninManagerBase (which require different setup procedures.
 class FakeSigninManagerForSyncUIUtilTest : public FakeSigninManagerBase {
  public:
   explicit FakeSigninManagerForSyncUIUtilTest(Profile* profile)
       : FakeSigninManagerBase(
             ChromeSigninClientFactory::GetForProfile(profile),
             AccountTrackerServiceFactory::GetForProfile(profile)),
         auth_in_progress_(false) {
-    Initialize(NULL);
+    Initialize(nullptr);
   }
 
   ~FakeSigninManagerForSyncUIUtilTest() override {}
 
   bool AuthInProgress() const override { return auth_in_progress_; }
 
   void set_auth_in_progress() {
     auth_in_progress_ = true;
   }
 
@@ skipping 228 matching lines @@
   // from previous one.
   status.sync_protocol_error.action = syncer::UPGRADE_CLIENT;
   EXPECT_CALL(service, QueryDetailedSyncStatus(_))
       .WillOnce(DoAll(SetArgPointee<0>(status), Return(true)));
   base::string16 upgrade_client_status_label;
   sync_ui_util::GetStatusLabels(profile.get(), &service, *signin,
                                 sync_ui_util::PLAIN_TEXT,
                                 &upgrade_client_status_label, &link_label);
   EXPECT_NE(unrecoverable_error_status_label, upgrade_client_status_label);
 }