[iOS] Fix incorrectly oriented frames when rapidly switching between cameras.

webrtc/sdk/objc/Framework/Classes/Video/AVCaptureSession+Device.h

Index: webrtc/sdk/objc/Framework/Classes/Video/AVCaptureSession+Device.h
diff --git a/webrtc/sdk/objc/Framework/Classes/Video/AVCaptureSession+Device.h b/webrtc/sdk/objc/Framework/Classes/Video/AVCaptureSession+Device.h
new file mode 100644
index 0000000000000000000000000000000000000000..960ca3e44b159be66536c07258cb8f138abce859
--- /dev/null
+++ b/webrtc/sdk/objc/Framework/Classes/Video/AVCaptureSession+Device.h
@@ -0,0 +1,23 @@
+/*
+ *  Copyright 2017 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 <AVFoundation/AVFoundation.h>
+#import <CoreMedia/CoreMedia.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface AVCaptureSession (Device)

[tkchin_webrtc, 2017/07/25 19:33:30]

DevicePosition?

+
+// Check the image's EXIF for the camera the image came from.
++ (AVCaptureDevicePosition)devicePositionForSampleBuffer:(CMSampleBufferRef)sampleBuffer;
+
+@end
+
+NS_ASSUME_NONNULL_END