Refactoring: Create per-connection packet writers in QuicDispatcher.

net/quic/quic_server_test.cc

Index: net/quic/quic_server_test.cc
diff --git a/net/quic/quic_server_test.cc b/net/quic/quic_server_test.cc
index 74db34de240aed7a2607579c30212bc774c39406..5aa15241e8d170327279b6df01736921001745ee 100644
--- a/net/quic/quic_server_test.cc
+++ b/net/quic/quic_server_test.cc
@@ -22,7 +22,10 @@ class QuicChromeServerDispatchPacketTest : public ::testing::Test {
  public:
   QuicChromeServerDispatchPacketTest()
       : crypto_config_("blah", QuicRandom::GetInstance()),
-        dispatcher_(config_, crypto_config_, &helper_) {
+        dispatcher_(config_,
+                    crypto_config_,
+                    new QuicDispatcher::DefaultPacketWriterFactory(),
+                    &helper_) {
     dispatcher_.Initialize(NULL);
   }