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

chrome/browser/sync/test/integration/sync_test.h

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_SYNC_TEST_INTEGRATION_SYNC_TEST_H_
 #define CHROME_BROWSER_SYNC_TEST_INTEGRATION_SYNC_TEST_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 219 matching lines @@
   // only if ServerSupportsErrorTriggering() returned true.
   void TriggerMigrationDoneError(syncer::ModelTypeSet model_types);
 
   // Triggers an XMPP auth error on the server.  Note the server will
   // stay in this state until shut down.
   void TriggerXmppAuthError();
 
   // Triggers the creation the Synced Bookmarks folder on the server.
   void TriggerCreateSyncedBookmarks();
 
-  // Returns the FakeServer being used for the test or NULL if FakeServer is
+  // Returns the FakeServer being used for the test or null if FakeServer is
   // not being used.
   fake_server::FakeServer* GetFakeServer() const;
 
   // Triggers a sync for the given |model_types| for the Profile at |index|.
   void TriggerSyncForModelTypes(int index, syncer::ModelTypeSet model_types);
 
  protected:
   // Add custom switches needed for running the test.
   virtual void AddTestSwitches(base::CommandLine* cl);
 
@@ skipping 208 matching lines @@
   std::unique_ptr<net::URLFetcherImplFactory> factory_;
 
   // The contents to be written to a profile's Preferences file before the
   // Profile object is created. If empty, no preexisting file will be written.
   std::string preexisting_preferences_file_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncTest);
 };
 
 #endif  // CHROME_BROWSER_SYNC_TEST_INTEGRATION_SYNC_TEST_H_