Switch base::Value typemapping to be by value instead of by unique_ptr.

chrome/browser/safe_browsing/incident_reporting/preference_validation_delegate.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 "chrome/browser/safe_browsing/incident_reporting/preference_validation_delegate.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 44 matching lines @@
 PreferenceValidationDelegate::PreferenceValidationDelegate(
     Profile* profile,
     std::unique_ptr<IncidentReceiver> incident_receiver)
     : profile_(profile), incident_receiver_(std::move(incident_receiver)) {}
 
 PreferenceValidationDelegate::~PreferenceValidationDelegate() {
 }
 
 void PreferenceValidationDelegate::OnAtomicPreferenceValidation(
     const std::string& pref_path,
-    std::unique_ptr<base::Value> value,
+    const base::Optional<base::Value>& value,
     ValueState value_state,
     ValueState external_validation_value_state,
     bool is_personal) {
   TPIncident_ValueState proto_value_state =
       MapValueState(value_state, external_validation_value_state);
   if (proto_value_state != TPIncident::UNKNOWN) {
     std::unique_ptr<TPIncident> incident(
         new ClientIncidentReport_IncidentData_TrackedPreferenceIncident());
     incident->set_path(pref_path);
     if (!value ||
@@ skipping 36 matching lines @@
       }
     }
     incident->set_value_state(proto_value_state);
     incident_receiver_->AddIncidentForProfile(
         profile_, base::MakeUnique<TrackedPreferenceIncident>(
                       std::move(incident), is_personal));
   }
 }
 
 }  // namespace safe_browsing