Add ClientDimensions message to control channel.

remoting/host/client_session.h

Index: remoting/host/client_session.h
diff --git a/remoting/host/client_session.h b/remoting/host/client_session.h
index 41068fa6bcb2e740585b77631de7b34ec812b19b..a4f2367d90da0877e325175718ec0e0176ca6b0e 100644
--- a/remoting/host/client_session.h
+++ b/remoting/host/client_session.h
@@ -76,6 +76,10 @@ class ClientSession : public protocol::HostEventStub,
   virtual void InjectKeyEvent(const protocol::KeyEvent& event) OVERRIDE;
   virtual void InjectMouseEvent(const protocol::MouseEvent& event) OVERRIDE;
 
+  // protocol::HostStub interface.
+  virtual void NotifyClientDimensions(
+      const protocol::ClientDimensions& dimensions) OVERRIDE;
+
   // protocol::ConnectionToClient::EventHandler interface.
   virtual void OnConnectionAuthenticated(
       protocol::ConnectionToClient* connection) OVERRIDE;