Use ChannelMojo for remote security key channels.

remoting/host/security_key/remote_security_key_main.cc

Index: remoting/host/security_key/remote_security_key_main.cc
diff --git a/remoting/host/security_key/remote_security_key_main.cc b/remoting/host/security_key/remote_security_key_main.cc
index 728dd9bb8334e14871526134a0ce0aa680700473..1490b42f2b69a3fd1bfde8a7baaee3d7701b8f19 100644
--- a/remoting/host/security_key/remote_security_key_main.cc
+++ b/remoting/host/security_key/remote_security_key_main.cc
@@ -12,6 +12,9 @@
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "mojo/edk/embedder/embedder.h"
+#include "mojo/edk/embedder/scoped_ipc_support.h"
 #include "remoting/host/host_exit_codes.h"
 #include "remoting/host/logging.h"
 #include "remoting/host/security_key/security_key_ipc_client.h"
@@ -137,6 +140,9 @@ int StartRemoteSecurityKey() {
 #error Not implemented.
 #endif
 
+  mojo::edk::Init();
+  mojo::edk::ScopedIPCSupport ipc_support(base::ThreadTaskRunnerHandle::Get());
+
   base::RunLoop run_loop;
 
   std::unique_ptr<SecurityKeyIpcClient> ipc_client(new SecurityKeyIpcClient());