Add ClientDimensions message to 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 a52429a6fad21506f0a723bbcc05e619bbbabd7e..03c657c76d133ff920cc5f0e8ef9175f7305f8b3 100644
--- a/remoting/protocol/host_stub.h
+++ b/remoting/protocol/host_stub.h
@@ -14,13 +14,16 @@
 namespace remoting {
 namespace protocol {
 
+class ClientDimensions;
+
 class HostStub {
  public:
   HostStub() {}
   virtual ~HostStub() {}
 
-  // Currently we don't use the control channel for anything. Add new
-  // message handlers here when necessary.
+  // Notification of the available client display dimensions.
+  // This may be used to resize the host display to match the client area.
+  virtual void NotifyClientDimensions(const ClientDimensions& dimensions) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(HostStub);