Added JsonMessage to the control channel.

remoting/protocol/host_stub.h

Index: remoting/protocol/host_stub.h
diff --git a/remoting/protocol/host_stub.h b/remoting/protocol/host_stub.h
index 46d75346bd62d12431505a232c853bda86d48c56..cf9fa0b95c3fbaf95a79db5e2d0f95bd8617453c 100644
--- a/remoting/protocol/host_stub.h
+++ b/remoting/protocol/host_stub.h
@@ -17,6 +17,7 @@ namespace protocol {
 class AudioControl;
 class Capabilities;
 class ClientResolution;
+class ExtensionMessage;
 class PairingResponse;
 class PairingRequest;
 class VideoControl;
@@ -43,6 +44,9 @@ class HostStub {
   // Requests pairing between the host and client for PIN-less authentication.
   virtual void RequestPairing(const PairingRequest& pairing_request) = 0;
 
+  // Deliver an extension message from the client to the host.
+  virtual void DeliverClientMessage(const ExtensionMessage& message) = 0;
+
  protected:
   virtual ~HostStub() {}