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

Trying to display the Disconnect window causes rejection from the Window Server on
OS X 10.7.4, preventing the capturer from working.

BUG=140984
TEST=Verify Chromoting works on the system login screen.


Review URL: https://chromiumcodereview.appspot.com/10883033

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@153610 0039d316-1c4b-4281-b951-d872f2087c98

remoting/host/remoting_me2me_host.cc

@@ -246,8 +246,25 @@ 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();
 
@@ -517,9 +534,11 @@ 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();