Remove base::Value::CreateNullValue

tools/gn/desc_builder.cc

 // Copyright (c) 2016 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 <set>
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/config.h"
@@ skipping 104 matching lines @@
   template <typename T>
   ValuePtr RenderValue(const std::vector<T>& vector) {
     auto res = base::MakeUnique<base::ListValue>();
     for (const auto& v : vector)
       res->Append(RenderValue(v));
 
     return std::move(res);
   }
 
   ValuePtr RenderValue(const std::string& s, bool optional = false) {
-    return (s.empty() && optional) ? base::Value::CreateNullValue()
+    return (s.empty() && optional) ? base::MakeUnique<base::Value>()
                                    : ValuePtr(new base::Value(s));
   }
 
   ValuePtr RenderValue(const SourceDir& d) {
-    return d.is_null() ? base::Value::CreateNullValue()
+    return d.is_null() ? base::MakeUnique<base::Value>()
                        : ValuePtr(new base::Value(FormatSourceDir(d)));
   }
 
   ValuePtr RenderValue(const SourceFile& f) {
-    return f.is_null() ? base::Value::CreateNullValue()
+    return f.is_null() ? base::MakeUnique<base::Value>()
                        : ValuePtr(new base::Value(f.value()));
   }
 
   ValuePtr RenderValue(const LibFile& lib) {
     if (lib.is_source_file())
       return RenderValue(lib.source_file());
     return RenderValue(lib.value());
   }
 
   template <class VectorType>
@@ skipping 565 matching lines @@
 
 std::unique_ptr<base::DictionaryValue> DescBuilder::DescriptionForConfig(
     const Config* config,
     const std::string& what) {
   std::set<std::string> w;
   if (!what.empty())
     w.insert(what);
   ConfigDescBuilder b(config, w);
   return b.BuildDescription();
 }