Ensure Dxgi duplicator works correctly in session 0

webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc

Index: webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
diff --git a/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc b/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
index 331379b8a56d0e7307c500a810ac8336bdddb068..373f2cc761be897d3053e7a612324f9284606bcf 100644
--- a/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
+++ b/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
@@ -74,6 +74,11 @@ void ScreenCapturerWinDirectx::CaptureFrame() {
 
   using DuplicateResult = DxgiDuplicatorController::Result;
   switch (result) {
+    case DuplicateResult::UNSUPPORTED_SESSION: {
+      LOG(LS_ERROR) << "Current binary is running on an unsupported session.";

[Sergey Ulanov, 2017/06/28 01:29:59]

nit: Replace "an unsupported session" with "a session not supported by DirectX
screen capturer.

[Hzj_jie, 2017/06/28 05:01:58]

Done.

+      callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
+      break;
+    }
     case DuplicateResult::FRAME_PREPARE_FAILED: {
       LOG(LS_ERROR) << "Failed to allocate a new DesktopFrame.";
       // This usually means we do not have enough memory or SharedMemoryFactory