Bug 1817724 - [libwebrtc] Restore changes to RTCCameraVideoCapturer.m. r=webrtc-reviewers,ng

Differential Revision: https://phabricator.services.mozilla.com/D171961

third_party/libwebrtc/sdk/objc/components/capturer/RTCCameraVideoCapturer.m

@@ -186,7 +186,6 @@ const int64_t kNanosecondsPerSecond = 1000000000;
                       [self updateOrientation];
                       [self updateDeviceCaptureFormat:format fps:fps];
                       [self updateVideoDataOutputPixelFormat:format];
-                      [_videoDataOutput setSampleBufferDelegate:self queue:self.frameQueue];
                       [self.captureSession startRunning];
                       [self.currentDevice unlockForConfiguration];
                       self.isRunning = YES;
@@ -206,7 +205,6 @@ const int64_t kNanosecondsPerSecond = 1000000000;
                       for (AVCaptureDeviceInput *oldInput in [self.captureSession.inputs copy]) {
                         [self.captureSession removeInput:oldInput];
                       }
-                      [_videoDataOutput setSampleBufferDelegate:nil queue:nil];
                       [self.captureSession stopRunning];
 
 #if TARGET_OS_IPHONE
@@ -217,11 +215,6 @@ const int64_t kNanosecondsPerSecond = 1000000000;
                         }
                       });
 #endif
-
-                      // Wait for any pending captureOutput tasks.
-                      dispatch_sync(self.frameQueue, ^{
-                                    });
-
                       self.isRunning = NO;
                       if (completionHandler) {
                         completionHandler();
@@ -471,6 +464,7 @@ const int64_t kNanosecondsPerSecond = 1000000000;
   _outputPixelFormat = _preferredOutputPixelFormat;
   videoDataOutput.videoSettings = @{(NSString *)kCVPixelBufferPixelFormatTypeKey : pixelFormat};
   videoDataOutput.alwaysDiscardsLateVideoFrames = NO;
+  [videoDataOutput setSampleBufferDelegate:self queue:self.frameQueue];
   _videoDataOutput = videoDataOutput;
 }