[Chromoting] Improve DirectX capturer to support multiple outputs

webrtc/modules/desktop_capture/win/dxgi_context.cc

 /*
  *  Copyright 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.
  */
 
-#include "RTCUIApplication.h"
+#include "webrtc/modules/desktop_capture/win/dxgi_context.h"
 
-#if defined(WEBRTC_IOS)
+#include "webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h"
 
-#import <UIKit/UIKit.h>
+namespace webrtc {
 
-bool RTCIsUIApplicationActive() {
-  UIApplicationState state = [UIApplication sharedApplication].applicationState;
-  return state == UIApplicationStateActive;
+DxgiContext::~DxgiContext() {
+  DxgiDuplicatorController::Instance()->Unregister(this);
 }
 
-#endif // WEBRTC_IOS
+}  // namespace webrtc