Make protocol::ConnectionToClient an abstract interface.

remoting/protocol/protocol_mock_objects.cc

Index: remoting/protocol/protocol_mock_objects.cc
diff --git a/remoting/protocol/protocol_mock_objects.cc b/remoting/protocol/protocol_mock_objects.cc
index 90876360ca30e8c45c6959bf46ef991931c39db4..eef785152773984f8c55cd3953be927d332dd622 100644
--- a/remoting/protocol/protocol_mock_objects.cc
+++ b/remoting/protocol/protocol_mock_objects.cc
@@ -10,14 +10,9 @@
 namespace remoting {
 namespace protocol {
 
-MockConnectionToClient::MockConnectionToClient(Session* session,
+MockConnectionToClient::MockConnectionToClient(scoped_ptr<Session> session,
                                                HostStub* host_stub)
-    : ConnectionToClient(session),
-      clipboard_stub_(nullptr),
-      host_stub_(host_stub),
-      input_stub_(nullptr),
-      video_feedback_stub_(nullptr) {
-}
+    : session_(session.Pass()), host_stub_(host_stub) {}
 
 MockConnectionToClient::~MockConnectionToClient() {}