Add DesktopCapturerId and attach it to DesktopFrame

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 119 matching lines @@
         callback_->OnCaptureResult(Result::ERROR_TEMPORARY, nullptr);
       }
       return;
     }
   }
 
   std::unique_ptr<DesktopFrame> result = frames_.current_frame()->Share();
   result->set_capture_time_ms(
       (rtc::TimeNanos() - capture_start_time_nanos) /
       rtc::kNumNanosecsPerMillisec);
+  result->set_capturer_id(DesktopCapturerId::kScreenCapturerWinDirectx);
   callback_->OnCaptureResult(Result::SUCCESS, std::move(result));
 }
 
 bool ScreenCapturerWinDirectx::GetSourceList(SourceList* sources) {
   int screen_count = DxgiDuplicatorController::Instance()->ScreenCount();
   for (int i = 0; i < screen_count; i++) {
     sources->push_back({i});
   }
   return true;
 }
@@ skipping 14 matching lines @@
   int screen_count = DxgiDuplicatorController::Instance()->ScreenCount();
   if (id >= 0 && id < screen_count) {
     current_screen_id_ = id;
     context_.Reset();
     return true;
   }
   return false;
 }
 
 }  // namespace webrtc