[Sync] Migrate SyncInternalsMessageHandler off CallJavascriptFunctionUnsafe.

components/sync/engine/events/protocol_event.cc

Index: components/sync/engine/events/protocol_event.cc
diff --git a/components/sync/engine/events/protocol_event.cc b/components/sync/engine/events/protocol_event.cc
index 3f7f813eb7b6bb76438bd480b72316cf64277ef1..629b2bbf3f31b6b48bd54ef92f3979bfc7ec3a77 100644
--- a/components/sync/engine/events/protocol_event.cc
+++ b/components/sync/engine/events/protocol_event.cc
@@ -4,6 +4,10 @@
 
 #include "components/sync/engine/events/protocol_event.h"
 
+#include <utility>
+
+#include "base/memory/ptr_util.h"
+
 namespace syncer {
 
 ProtocolEvent::ProtocolEvent() {}
@@ -12,13 +16,11 @@ 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;
 }