Rotate frames correctly for back camera

media/capture/video/linux/video_capture_device_linux.h

Index: media/capture/video/linux/video_capture_device_linux.h
diff --git a/media/capture/video/linux/video_capture_device_linux.h b/media/capture/video/linux/video_capture_device_linux.h
index e8adbde8df41715bdd075c0c921c3f6446eb4383..abaa36b94a4bb93e75d3fd8b15e6320de5810152 100644
--- a/media/capture/video/linux/video_capture_device_linux.h
+++ b/media/capture/video/linux/video_capture_device_linux.h
@@ -59,6 +59,10 @@ class VideoCaptureDeviceLinux : public VideoCaptureDevice {
 
   const VideoCaptureDeviceDescriptor device_descriptor_;
 
+  // True if the camera is world-facing. False if the camera is user-facing,
+  // external, or unknown.
+  bool is_back_camera_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(VideoCaptureDeviceLinux);
 };