Added JsonMessage to the control channel.

remoting/protocol/client_stub.h

Index: remoting/protocol/client_stub.h
diff --git a/remoting/protocol/client_stub.h b/remoting/protocol/client_stub.h
index 4507ba7f821ad4dce84eef1fcd2dd50d6b76f165..d57f948d35ea36339c93a68f296d12f439b62545 100644
--- a/remoting/protocol/client_stub.h
+++ b/remoting/protocol/client_stub.h
@@ -18,6 +18,7 @@ namespace remoting {
 namespace protocol {
 
 class Capabilities;
+class ExtensionMessage;
 class PairingResponse;
 
 class ClientStub : public ClipboardStub,
@@ -32,6 +33,9 @@ class ClientStub : public ClipboardStub,
   // Passes a pairing response message to the client.
   virtual void SetPairingResponse(const PairingResponse& pairing_response) = 0;
 
+  // Deliver an extension message from the host to the client.
+  virtual void DeliverHostMessage(const ExtensionMessage& message) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ClientStub);
 };