Convert JsonWriter::Write to taking a const ref for the in-param

content/browser/android/tracing_controller_android.cc

Index: content/browser/android/tracing_controller_android.cc
diff --git a/content/browser/android/tracing_controller_android.cc b/content/browser/android/tracing_controller_android.cc
index 6953a0de5f85015cb0334cb5d0287a3ba9031130..5c14535abf5be1975c132926aa531c1172e80be3 100644
--- a/content/browser/android/tracing_controller_android.cc
+++ b/content/browser/android/tracing_controller_android.cc
@@ -91,14 +91,14 @@ bool TracingControllerAndroid::GetKnownCategoryGroupsAsync(JNIEnv* env,
 
 void TracingControllerAndroid::OnKnownCategoriesReceived(
     const std::set<std::string>& categories_received) {
-  scoped_ptr<base::ListValue> category_list(new base::ListValue());
+  base::ListValue category_list;
   for (std::set<std::string>::const_iterator it = categories_received.begin();
        it != categories_received.end();
        ++it) {
-    category_list->AppendString(*it);
+    category_list.AppendString(*it);
   }
   std::string received_category_list;
-  base::JSONWriter::Write(category_list.get(), &received_category_list);
+  base::JSONWriter::Write(category_list, &received_category_list);
 
   // This log is required by adb_profile_chrome.py.
   LOG(WARNING) << "{\"traceCategoriesList\": " << received_category_list << "}";