Ensure Dxgi duplicator works correctly in session 0

webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 56 matching lines @@
   DxgiDuplicatorController::Result result;
   if (current_screen_id_ == kFullDesktopScreenId) {
     result = controller_->Duplicate(frames_.current_frame());
   } else {
     result = controller_->DuplicateMonitor(
         frames_.current_frame(), current_screen_id_);
   }
 
   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
       // cannot work correctly.
       callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
       break;
     }
     case DuplicateResult::INVALID_MONITOR_ID: {
       callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
       break;
@@ skipping 36 matching lines @@
 
   int screen_count = controller_->ScreenCount();
   if (id >= 0 && id < screen_count) {
     current_screen_id_ = id;
     return true;
   }
   return false;
 }
 
 }  // namespace webrtc