Move Quic AppendTimestampFrame method out of AppendCongestionFrame.

net/quic/congestion_control/hybrid_slow_start_test.cc

Index: net/quic/congestion_control/hybrid_slow_start_test.cc
diff --git a/net/quic/congestion_control/hybrid_slow_start_test.cc b/net/quic/congestion_control/hybrid_slow_start_test.cc
index 91c5d9f2d6529399ff12f2597e4bf3b8daa804d7..bea5840ab793f09f7beb92fa201d6a475455dcb1 100644
--- a/net/quic/congestion_control/hybrid_slow_start_test.cc
+++ b/net/quic/congestion_control/hybrid_slow_start_test.cc
@@ -53,7 +53,7 @@ TEST_F(HybridSlowStartTest, Simple) {
 // TODO(ianswett): Add tests which more realistically invoke the methods,
 // simulating how actual acks arrive and packets are sent.
 TEST_F(HybridSlowStartTest, AckTrain) {
-  // At a typical RTT 60 ms, assuming that the inter arrival is 1 ms,
+  // At a typical RTT 60 ms, assuming that the inter arrival timestamp is 1 ms,
   // we expect to be able to send a burst of 30 packet before we trigger the
   // ack train detection.
   const int kMaxLoopCount = 5;