Add new view that renders local video using AVCaptureLayerPreview.

talk/app/webrtc/objc/avfoundationvideocapturer.mm

 /*
  * libjingle
  * Copyright 2015 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 36 matching lines @@
 static dispatch_queue_t kBackgroundQueue = nil;
 
 // This class used to capture frames using AVFoundation APIs on iOS. It is meant
 // to be owned by an instance of AVFoundationVideoCapturer. The reason for this
 // because other webrtc objects own cricket::VideoCapturer, which is not
 // ref counted. To prevent bad behavior we do not expose this class directly.
 @interface RTCAVFoundationVideoCapturerInternal : NSObject
     <AVCaptureVideoDataOutputSampleBufferDelegate>
 
 @property(nonatomic, readonly) AVCaptureSession* captureSession;
+@property(nonatomic, readonly) dispatch_queue_t captureSessionQueue;
 @property(nonatomic, readonly) BOOL isRunning;
 @property(nonatomic, assign) BOOL useBackCamera;  // Defaults to NO.
 
 // We keep a pointer back to AVFoundationVideoCapturer to make callbacks on it
 // when we receive frames. This is safe because this object should be owned by
 // it.
 - (instancetype)initWithCapturer:(webrtc::AVFoundationVideoCapturer*)capturer;
 - (void)startCaptureAsync;
 - (void)stopCaptureAsync;
 
@@ skipping 43 matching lines @@
   }
   return self;
 }
 
 - (void)dealloc {
   [self stopCaptureAsync];
   [[NSNotificationCenter defaultCenter] removeObserver:self];
   _capturer = nullptr;
 }
 
+- (dispatch_queue_t)captureSessionQueue {
+  return kBackgroundQueue;
+}
+
 - (void)setUseBackCamera:(BOOL)useBackCamera {
   if (_useBackCamera == useBackCamera) {
     return;
   }
   _useBackCamera = useBackCamera;
   [self updateSessionInput];
 }
 
 - (void)startCaptureAsync {
   if (_isRunning) {
@@ skipping 234 matching lines @@
 }
 
 void AVFoundationVideoCapturer::SetUseBackCamera(bool useBackCamera) {
   _capturer.useBackCamera = useBackCamera;
 }
 
 bool AVFoundationVideoCapturer::GetUseBackCamera() const {
   return _capturer.useBackCamera;
 }
 
+dispatch_queue_t AVFoundationVideoCapturer::GetCaptureSessionQueue() {
+  return _capturer.captureSessionQueue;
+}
+
 void AVFoundationVideoCapturer::CaptureSampleBuffer(
     CMSampleBufferRef sampleBuffer) {
   if (CMSampleBufferGetNumSamples(sampleBuffer) != 1 ||
       !CMSampleBufferIsValid(sampleBuffer) ||
       !CMSampleBufferDataIsReady(sampleBuffer)) {
     return;
   }
 
   CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
   if (imageBuffer == NULL) {
@@ skipping 54 matching lines @@
 
 void AVFoundationVideoCapturer::SignalFrameCapturedOnStartThread(
     const cricket::CapturedFrame* frame) {
   RTC_DCHECK(_startThread->IsCurrent());
   // This will call a superclass method that will perform the frame conversion
   // to I420.
   SignalFrameCaptured(this, frame);
 }
 
 }  // namespace webrtc