Remove ListValue::Append(new {Fundamental,String}Value(...)) pattern in //chrome

chrome/browser/tracing/chrome_tracing_delegate.cc

 // Copyright 2015 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/tracing/chrome_tracing_delegate.h"
 
 #include <utility>
 
 #include "base/time/time.h"
 #include "build/build_config.h"
@@ skipping 146 matching lines @@
 }
 
 void ChromeTracingDelegate::GenerateMetadataDict(
     base::DictionaryValue* metadata_dict) {
   DCHECK(metadata_dict);
   std::vector<std::string> variations;
   variations::GetFieldTrialActiveGroupIdsAsStrings(&variations);
 
   std::unique_ptr<base::ListValue> variations_list(new base::ListValue());
   for (const auto& it : variations)
-    variations_list->Append(new base::StringValue(it));
+    variations_list->AppendString(it);
 
   metadata_dict->Set("field-trials", std::move(variations_list));
 }
 
 content::MetadataFilterPredicate
 ChromeTracingDelegate::GetMetadataFilterPredicate() {
   return base::Bind(&IsMetadataWhitelisted);
 }