Pass the |curtain_activated| flag to IpcDesktopEnvironmentFactory.

remoting/remoting.gyp

Index: remoting/remoting.gyp
diff --git a/remoting/remoting.gyp b/remoting/remoting.gyp
index 02430eb2378b3d9db63c7a2c28dd966ec0fa7da9..daf3619073f00f331cf97be74b8f6edf21f50f08 100644
--- a/remoting/remoting.gyp
+++ b/remoting/remoting.gyp
@@ -20,6 +20,7 @@
     },
 
     'remoting_multi_process%': '<(remoting_multi_process)',
+    'remoting_rdp_session%': 0,
     'remoting_use_apps_v2%': 0,
 
     # The |major|, |build| and |patch| versions are inherited from Chrome.
@@ -264,6 +265,12 @@
           'REMOTING_ENABLE_BREAKPAD'
         ],
       }],
+      ['OS=="win" and remoting_multi_process != 0 and \
+          remoting_rdp_session != 0', {
+        'defines': [
+          'REMOTING_RDP_SESSION',
+        ],
+      }],
       ['remoting_multi_process != 0', {
         'defines': [
           'REMOTING_MULTI_PROCESS',