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

chrome/browser/sync/sync_global_error_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 "chrome/browser/sync/sync_global_error.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 14 matching lines @@
 
 using ::testing::NiceMock;
 using ::testing::Return;
 using ::testing::ReturnRef;
 using ::testing::_;
 
 namespace {
 
 class FakeLoginUIService: public LoginUIService {
  public:
-  FakeLoginUIService() : LoginUIService(NULL) {}
+  FakeLoginUIService() : LoginUIService(nullptr) {}
 };
 
 class FakeLoginUI : public LoginUIService::LoginUI {
  public:
   FakeLoginUI() : focus_ui_call_count_(0) {}
 
   ~FakeLoginUI() override {}
 
   int focus_ui_call_count() const { return focus_ui_call_count_; }
 
@@ skipping 123 matching lines @@
               .WillRepeatedly(Return(true));
   EXPECT_CALL(service, IsPassphraseRequiredForDecryption())
               .WillRepeatedly(Return(true));
   VerifySyncGlobalErrorResult(
       &service, login_ui_service, browser(), &error, &global_error,
       GoogleServiceAuthError::INVALID_GAIA_CREDENTIALS,
       false /* not signed in */, false /* no error */);
 
   global_error.Shutdown();
 }