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

remoting/protocol/protocol_mock_objects.h

Index: remoting/protocol/protocol_mock_objects.h
diff --git a/remoting/protocol/protocol_mock_objects.h b/remoting/protocol/protocol_mock_objects.h
index 20a56b34d785badd9e407aa1e5abeb404699cc5b..a5e9f2dd09f1ea64a0be8d0faf20b607afc270df 100644
--- a/remoting/protocol/protocol_mock_objects.h
+++ b/remoting/protocol/protocol_mock_objects.h
@@ -10,6 +10,7 @@
 #include "net/base/ip_endpoint.h"
 #include "remoting/proto/internal.pb.h"
 #include "remoting/protocol/client_stub.h"
+#include "remoting/protocol/clipboard_stub.h"
 #include "remoting/protocol/connection_to_client.h"
 #include "remoting/protocol/host_stub.h"
 #include "remoting/protocol/input_stub.h"
@@ -59,6 +60,17 @@ class MockConnectionToClientEventHandler :
   DISALLOW_COPY_AND_ASSIGN(MockConnectionToClientEventHandler);
 };
 
+class MockClipboardStub : public ClipboardStub {
+ public:
+  MockClipboardStub();
+  virtual ~MockClipboardStub();
+
+  MOCK_METHOD1(InjectClipboardEvent, void(const ClipboardEvent& event));
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MockClipboardStub);
+};
+
 class MockInputStub : public InputStub {
  public:
   MockInputStub();