Add ifdef protection for iOS-only headers

webrtc/sdk/objc/Framework/Headers/WebRTC/WebRTC.h

 /*
  *  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.
  */
 
 #import <WebRTC/RTCAVFoundationVideoSource.h>
 #import <WebRTC/RTCAudioSource.h>
 #import <WebRTC/RTCAudioTrack.h>
+#if TARGET_OS_IPHONE
 #import <WebRTC/RTCCameraPreviewView.h>
+#endif
 #import <WebRTC/RTCConfiguration.h>
 #import <WebRTC/RTCDataChannel.h>
 #import <WebRTC/RTCDataChannelConfiguration.h>
 #import <WebRTC/RTCDispatcher.h>
+#if TARGET_OS_IPHONE
 #import <WebRTC/RTCEAGLVideoView.h>
+#endif
 #import <WebRTC/RTCFieldTrials.h>
 #import <WebRTC/RTCFileLogger.h>
 #import <WebRTC/RTCIceCandidate.h>
 #import <WebRTC/RTCIceServer.h>
 #import <WebRTC/RTCLegacyStatsReport.h>
 #import <WebRTC/RTCLogging.h>
 #import <WebRTC/RTCMacros.h>
 #import <WebRTC/RTCMediaConstraints.h>
 #import <WebRTC/RTCMediaSource.h>
 #import <WebRTC/RTCMediaStream.h>
 #import <WebRTC/RTCMediaStreamTrack.h>
 #import <WebRTC/RTCMetrics.h>
 #import <WebRTC/RTCMetricsSampleInfo.h>
 #import <WebRTC/RTCPeerConnection.h>
 #import <WebRTC/RTCPeerConnectionFactory.h>
 #import <WebRTC/RTCRtpCodecParameters.h>
 #import <WebRTC/RTCRtpEncodingParameters.h>
 #import <WebRTC/RTCRtpParameters.h>
 #import <WebRTC/RTCRtpReceiver.h>
 #import <WebRTC/RTCRtpSender.h>
 #import <WebRTC/RTCSSLAdapter.h>
 #import <WebRTC/RTCSessionDescription.h>
 #import <WebRTC/RTCTracing.h>
 #import <WebRTC/RTCVideoFrame.h>
 #import <WebRTC/RTCVideoRenderer.h>
 #import <WebRTC/RTCVideoSource.h>
 #import <WebRTC/RTCVideoTrack.h>
+#if TARGET_OS_IPHONE
 #import <WebRTC/UIDevice+RTCDevice.h>
+#endif