Remove raw DictionaryValue::Set in //chrome

chrome/test/chromedriver/chrome_launcher.cc

Index: chrome/test/chromedriver/chrome_launcher.cc
diff --git a/chrome/test/chromedriver/chrome_launcher.cc b/chrome/test/chromedriver/chrome_launcher.cc
index 58b0d1db238daee107738693d6df07fc35caad22..22a7d37c4d3efc9decfd15baaf82eadb6f52e0ed 100644
--- a/chrome/test/chromedriver/chrome_launcher.cc
+++ b/chrome/test/chromedriver/chrome_launcher.cc
@@ -6,6 +6,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+
 #include <algorithm>
 #include <memory>
 #include <utility>
@@ -21,6 +22,7 @@
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
+#include "base/memory/ptr_util.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/process/process.h"
@@ -816,7 +818,7 @@ Status WritePrefsFile(
   if (custom_prefs) {
     for (base::DictionaryValue::Iterator it(*custom_prefs); !it.IsAtEnd();
          it.Advance()) {
-      prefs->Set(it.key(), it.value().DeepCopy());
+      prefs->Set(it.key(), base::MakeUnique<base::Value>(it.value()));
     }
   }