Implemented local login check for PAM (only enabled on Linux for now).

remoting/host/remoting_me2me_host.cc

Index: remoting/host/remoting_me2me_host.cc
diff --git a/remoting/host/remoting_me2me_host.cc b/remoting/host/remoting_me2me_host.cc
index 2b8b28b3ce1a76b849f7bf90c68caae84891e984..9472a610c60eb1acc7c332c8aff46f41b3a7331e 100644
--- a/remoting/host/remoting_me2me_host.cc
+++ b/remoting/host/remoting_me2me_host.cc
@@ -78,6 +78,7 @@
 
 #if defined(OS_LINUX)
 #include "remoting/host/audio_capturer_linux.h"
+#include "remoting/host/pam_authorization_factory_posix.h"
 #endif  // defined(OS_LINUX)
 
 // N.B. OS_WIN is defined by including src/base headers.
@@ -393,6 +394,10 @@ void HostProcess::CreateAuthenticatorFactory() {
   scoped_ptr<protocol::AuthenticatorFactory> factory(
       new protocol::Me2MeHostAuthenticatorFactory(
           local_certificate, *key_pair_.private_key(), host_secret_hash_));
+#if defined(OS_LINUX)
+  // On Linux, perform a PAM authorization step after authentication.
+  factory.reset(new PamAuthorizationFactory(factory.Pass()));
+#endif
   host_->SetAuthenticatorFactory(factory.Pass());
 }