Don't use deprecated ListValue::Append(Value*) overload.

net/log/trace_net_log_observer_unittest.cc

Index: net/log/trace_net_log_observer_unittest.cc
diff --git a/net/log/trace_net_log_observer_unittest.cc b/net/log/trace_net_log_observer_unittest.cc
index 5c63f41f7690ac77cc0f64190b6af728fe847923..1844067a38b1f9ff82b0a726d4ecd090d0135dbd 100644
--- a/net/log/trace_net_log_observer_unittest.cc
+++ b/net/log/trace_net_log_observer_unittest.cc
@@ -127,7 +127,7 @@ class TraceNetLogObserverTest : public testing::Test {
       }
       if (category != kNetLogTracingCategory)
         continue;
-      filtered_trace_events->Append(dict->DeepCopy());
+      filtered_trace_events->Append(dict->CreateDeepCopy());
     }
     return filtered_trace_events;
   }