[Sync] Replacing NULL with nullptr in code and null in comments for components/sync/

components/sync/syncable/test_user_share.h

 // 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.
 //
 // A handy class that takes care of setting up and destroying a
 // UserShare instance for unit tests that require one.
 //
 // The expected usage is to make this a component of your test fixture:
 //
 //   class AwesomenessTest : public testing::Test {
@@ skipping 47 matching lines @@
 
   // Undo everything done by SetUp(): closes the UserShare and deletes
   // the backing files. Before closing the directory, this will run
   // the directory invariant checks and perform the SaveChanges action
   // on the user share's directory.
   void TearDown();
 
   // Save and reload Directory to clear out temporary data in memory.
   bool Reload();
 
-  // Non-NULL iff called between a call to SetUp() and TearDown().
+  // Non-null iff called between a call to SetUp() and TearDown().
   UserShare* user_share();
 
   // Sync's encryption handler. Used by tests to invoke the sync encryption
   // methods normally handled via the SyncBackendHost
   SyncEncryptionHandler* encryption_handler();
 
   // Returns the directory's transaction observer.  This transaction observer
   // has methods which can be helpful when writing test assertions.
   syncable::TestTransactionObserver* transaction_observer();
 
   // A helper function to pretend to download this type's root node.
   static bool CreateRoot(ModelType model_type, UserShare* service);
 
   size_t GetDeleteJournalSize() const;
 
  private:
   std::unique_ptr<TestDirectorySetterUpper> dir_maker_;
   std::unique_ptr<UserShare> user_share_;
 
   DISALLOW_COPY_AND_ASSIGN(TestUserShare);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_SYNCABLE_TEST_USER_SHARE_H_