Refactoring: Create per-connection packet writers in QuicDispatcher.

net/tools/quic/test_tools/quic_test_utils.h

Index: net/tools/quic/test_tools/quic_test_utils.h
diff --git a/net/tools/quic/test_tools/quic_test_utils.h b/net/tools/quic/test_tools/quic_test_utils.h
index b6449d33f2dc2beaaab16086f2443e63a8f38829..1eca03b0290d4abdf8375fc8dde87eb757030e2e 100644
--- a/net/tools/quic/test_tools/quic_test_utils.h
+++ b/net/tools/quic/test_tools/quic_test_utils.h
@@ -14,6 +14,8 @@
 #include "net/quic/quic_packet_writer.h"
 #include "net/quic/quic_session.h"
 #include "net/spdy/spdy_framer.h"
+#include "net/tools/quic/quic_dispatcher.h"
+#include "net/tools/quic/quic_per_connection_packet_writer.h"
 #include "net/tools/quic/quic_server_session.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -158,6 +160,46 @@ class MockAckNotifierDelegate : public QuicAckNotifier::DelegateInterface {
   DISALLOW_COPY_AND_ASSIGN(MockAckNotifierDelegate);
 };
 
+// Creates per-connection packet writers that register themselves with the
+// TestWriterFactory on each write so that TestWriterFactory::OnPacketSent can
+// be routed to the appropriate QuicConnection.
+class TestWriterFactory : public QuicDispatcher::PacketWriterFactory {
+ public:
+  TestWriterFactory();
+  virtual ~TestWriterFactory();
+
+  virtual QuicPacketWriter* Create(QuicPacketWriter* writer,
+                                   QuicConnection* connection) override;
+
+  // Calls OnPacketSent on the last QuicConnection to write through one of the
+  // packet writers created by this factory.
+  void OnPacketSent(WriteResult result);
+
+ private:
+  class PerConnectionPacketWriter : public QuicPerConnectionPacketWriter {
+   public:
+    PerConnectionPacketWriter(TestWriterFactory* factory,
+                              QuicPacketWriter* writer,
+                              QuicConnection* connection);
+    virtual ~PerConnectionPacketWriter();
+
+    virtual WriteResult WritePacket(
+        const char* buffer,
+        size_t buf_len,
+        const IPAddressNumber& self_address,
+        const IPEndPoint& peer_address) OVERRIDE;
+
+   private:
+    TestWriterFactory* factory_;
+  };
+
+  // If an asynchronous write is happening and |writer| gets deleted, this
+  // clears the pointer to it to prevent use-after-free.
+  void Unregister(PerConnectionPacketWriter* writer);
+
+  PerConnectionPacketWriter* current_writer_;
+};
+
 }  // namespace test
 }  // namespace tools
 }  // namespace net