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

components/sync/driver/glue/sync_backend_host_mock.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 COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_MOCK_H_
 #define COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_MOCK_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "components/sync/base/weak_handle.h"
 #include "components/sync/driver/glue/sync_backend_host.h"
 
 namespace syncer {
 
 // A mock of the SyncBackendHost.
 //
 // This class implements the bare minimum required for the ProfileSyncService to
-// get through initialization.  It often returns NULL pointers or nonesense
+// get through initialization.  It often returns null pointers or nonesense
 // values; it is not intended to be used in tests that depend on SyncBackendHost
 // behavior.
 class SyncBackendHostMock : public SyncBackendHost {
  public:
   SyncBackendHostMock();
   ~SyncBackendHostMock() override;
 
   void Initialize(
       SyncFrontend* frontend,
       std::unique_ptr<base::Thread> sync_thread,
@@ skipping 82 matching lines @@
 
   void set_fail_initial_download(bool should_fail);
 
  private:
   bool fail_initial_download_;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_MOCK_H_