Add the plumbing that will carry a clipboard item from a chromoting client to a host.

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 09a169dbc49d6f0089983b5d1504faf4454e1065..3596286d2de3af73ba11037e15bf9fc36b90d48a 100644
--- a/remoting/protocol/protocol_mock_objects.cc
+++ b/remoting/protocol/protocol_mock_objects.cc
@@ -25,6 +25,10 @@ MockConnectionToClientEventHandler::MockConnectionToClientEventHandler() {}
 
 MockConnectionToClientEventHandler::~MockConnectionToClientEventHandler() {}
 
+MockClipboardStub::MockClipboardStub() {}
+
+MockClipboardStub::~MockClipboardStub() {}
+
 MockInputStub::MockInputStub() {}
 
 MockInputStub::~MockInputStub() {}