[Sync] Migrate SyncInternalsMessageHandler off CallJavascriptFunctionUnsafe.

components/sync/engine/events/protocol_event.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/engine/events/protocol_event.h"
 
+#include <utility>
+
+#include "base/memory/ptr_util.h"
+
 namespace syncer {
 
 ProtocolEvent::ProtocolEvent() {}
 
 ProtocolEvent::~ProtocolEvent() {}
 
 std::unique_ptr<base::DictionaryValue> ProtocolEvent::ToValue(
     const ProtocolEvent& event) {
-  std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
-
+  auto dict = base::MakeUnique<base::DictionaryValue>();
   dict->SetDouble("time", event.GetTimestamp().ToJsTime());
   dict->SetString("type", event.GetType());
   dict->SetString("details", event.GetDetails());
-  dict->Set("proto", event.GetProtoMessage().release());
-
+  dict->Set("proto", event.GetProtoMessage());
   return dict;
 }
 
 }  // namespace syncer