Decouple Blimp transport output from BlimpConnections using MessagePort.

blimp/net/test_common.h

Index: blimp/net/test_common.h
diff --git a/blimp/net/test_common.h b/blimp/net/test_common.h
index c726feba5a8c2645cf72d5f2d4e59f95fba64786..54d1b330a77dc6ab4c4c104c2db1fd20618cda74 100644
--- a/blimp/net/test_common.h
+++ b/blimp/net/test_common.h
@@ -17,6 +17,7 @@
 #include "blimp/net/blimp_transport.h"
 #include "blimp/net/connection_error_observer.h"
 #include "blimp/net/connection_handler.h"
+#include "blimp/net/message_port.h"
 #include "blimp/net/packet_reader.h"
 #include "blimp/net/packet_writer.h"
 #include "net/socket/stream_socket.h"
@@ -139,9 +140,9 @@ class MockTransport : public BlimpTransport {
   ~MockTransport() override;
 
   MOCK_METHOD1(Connect, void(const net::CompletionCallback& callback));
-  MOCK_METHOD0(TakeConnectionPtr, BlimpConnection*());
+  MOCK_METHOD0(TakeMessagePortPtr, MessagePort*());
 
-  std::unique_ptr<BlimpConnection> TakeConnection() override;
+  std::unique_ptr<MessagePort> TakeMessagePort() override;
   const char* GetName() const override;
 };