remoting_me2me_host: Don't try to display UI on top of Mac login screen

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 be25fa363bd9e0e28aa3ef1fa00777313f1a5ae9..2231d357f677182fc56c88d371a4513693a010de 100644
--- a/remoting/host/remoting_me2me_host.cc
+++ b/remoting/host/remoting_me2me_host.cc
@@ -249,8 +249,25 @@ class HostProcess
     }
 
 #if defined(OS_MACOSX) || defined(OS_WIN)
-    host_user_interface_.reset(new HostUserInterface(context_.get()));
-#endif
+    bool want_user_interface = true;
+
+#if defined(OS_MACOSX)
+    // Don't try to display any UI on top of the system's login screen as this
+    // is rejected by the Window Server on OS X 10.7.4, and prevents the
+    // capturer from working (http://crbug.com/140984).
+    base::mac::ScopedCFTypeRef<CFDictionaryRef> session(
+        CGSessionCopyCurrentDictionary());
+    const void* logged_in = CFDictionaryGetValue(session,
+                                                 kCGSessionLoginDoneKey);
+    if (logged_in != kCFBooleanTrue) {
+      want_user_interface = false;
+    }
+#endif  // OS_MACOSX
+
+    if (want_user_interface) {
+      host_user_interface_.reset(new HostUserInterface(context_.get()));
+    }
+#endif  // OS_MACOSX || OS_WIN
 
     StartWatchingPolicy();
 
@@ -520,9 +537,11 @@ class HostProcess
     host_event_logger_ = HostEventLogger::Create(host_, kApplicationName);
 
 #if defined(OS_MACOSX) || defined(OS_WIN)
-    host_user_interface_->Start(
-        host_, base::Bind(&HostProcess::OnDisconnectRequested,
-                          base::Unretained(this)));
+    if (host_user_interface_.get()) {
+      host_user_interface_->Start(
+          host_, base::Bind(&HostProcess::OnDisconnectRequested,
+                            base::Unretained(this)));
+    }
 #endif
 
     host_->Start();