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

components/sync_sessions/session_data_type_controller_unittest.cc

 // Copyright 2014 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 "components/sync_sessions/session_data_type_controller.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 29 matching lines @@
   bool HasWindow() const override { return false; }
   SessionID::id_type GetSessionId() const override { return 0; }
   int GetTabCount() const override { return 0; }
   int GetActiveIndex() const override { return 0; }
   bool IsApp() const override { return false; }
   bool IsTypeTabbed() const override { return false; }
   bool IsTypePopup() const override { return false; }
   bool IsTabPinned(const SyncedTabDelegate* tab) const override {
     return false;
   }
-  SyncedTabDelegate* GetTabAt(int index) const override { return NULL; }
+  SyncedTabDelegate* GetTabAt(int index) const override { return nullptr; }
   SessionID::id_type GetTabIdAt(int index) const override { return 0; }
 
   bool IsSessionRestoreInProgress() const override {
     return is_restore_in_progress_;
   }
 
   bool ShouldSync() const override { return false; }
 
   void SetSessionRestoreInProgress(bool is_restore_in_progress) {
     is_restore_in_progress_ = is_restore_in_progress;
@@ skipping 192 matching lines @@
   EXPECT_EQ(syncer::DataTypeController::MODEL_STARTING, controller()->state());
 
   local_device()->SetInitialized(true);
   EXPECT_EQ(syncer::DataTypeController::MODEL_LOADED, controller()->state());
   EXPECT_TRUE(LoadResult());
 }
 
 }  // namespace
 
 }  // namespace sync_sessions