Simplify a string allocation and append into a single allocation

net/quic/test_tools/simple_quic_framer.cc

Index: net/quic/test_tools/simple_quic_framer.cc
diff --git a/net/quic/test_tools/simple_quic_framer.cc b/net/quic/test_tools/simple_quic_framer.cc
index c4d36b26e517d02bdcab3c3f2a7aecc39c716486..48a72d2ff5c2b29cbc7b70fb44bdd8faac8b0bb5 100644
--- a/net/quic/test_tools/simple_quic_framer.cc
+++ b/net/quic/test_tools/simple_quic_framer.cc
@@ -52,8 +52,7 @@ class SimpleFramerVisitor : public QuicFramerVisitorInterface {
 
   bool OnStreamFrame(const QuicStreamFrame& frame) override {
     // Save a copy of the data so it is valid after the packet is processed.
-    string* string_data = new string();
-    string_data->append(frame.data_buffer, frame.data_length);
+    string* string_data = new string(frame.data_buffer, frame.data_length);
     stream_data_.push_back(base::WrapUnique(string_data));
     // TODO(ianswett): A pointer isn't necessary with emplace_back.
     stream_frames_.push_back(base::MakeUnique<QuicStreamFrame>(