Do not rotate frames from external cameras

media/capture/video/linux/video_capture_device_chromeos.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/capture/video/linux/video_capture_device_chromeos.h"
 
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/macros.h"
@@ skipping 92 matching lines @@
     scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
     const VideoCaptureDeviceDescriptor& device_descriptor)
     : VideoCaptureDeviceLinux(device_descriptor),
       screen_observer_delegate_(
           new ScreenObserverDelegate(this, ui_task_runner)),
       lens_facing_(
           GetCameraConfig()->GetCameraFacing(device_descriptor.device_id,
                                              device_descriptor.model_id)),
       camera_orientation_(
           GetCameraConfig()->GetOrientation(device_descriptor.device_id,
-                                            device_descriptor.model_id)) {}
+                                            device_descriptor.model_id)),
+      // External cameras have lens_facing as MEDIA_VIDEO_FACING_NONE.
+      // We don't want to rotate the frame even if the device rotates.
+      rotates_with_device_(lens_facing_ !=
+                           VideoFacingMode::MEDIA_VIDEO_FACING_NONE) {}
 
 VideoCaptureDeviceChromeOS::~VideoCaptureDeviceChromeOS() {
   screen_observer_delegate_->RemoveObserver();
 }
 
 void VideoCaptureDeviceChromeOS::SetRotation(int rotation) {
-  // We assume external camera is facing the users. If not, the users can
-  // rotate the camera manually by themselves.
-  if (lens_facing_ == VideoFacingMode::MEDIA_VIDEO_FACING_ENVIRONMENT) {
+  if (!rotates_with_device_) {
+    rotation = 0;
+  } else if (lens_facing_ == VideoFacingMode::MEDIA_VIDEO_FACING_ENVIRONMENT) {
     // Original frame when |rotation| = 0
     // -----------------------
     // |          *          |
     // |         * *         |
     // |        *   *        |
     // |       *******       |
     // |      *       *      |
     // |     *         *     |
     // -----------------------
     //
@@ skipping 13 matching lines @@
     // |      ****   *       |
     // |    ***      *       |
     // |    ***      *       |
     // |      ****   *       |
     // |         ********    |
     // -----------------------
     //
     // Therefore, for back camera, we need to rotate (360 - |rotation|).
     rotation = (360 - rotation) % 360;
   }
-  // Take into account camera orientation w.r.t. the display.
+  // Take into account camera orientation w.r.t. the display. External cameras
+  // would have camera_orientation_ as 0.
   rotation = (rotation + camera_orientation_) % 360;
   VideoCaptureDeviceLinux::SetRotation(rotation);
 }
 
 void VideoCaptureDeviceChromeOS::SetDisplayRotation(
     const display::Display& display) {
   if (display.IsInternal())
     SetRotation(display.rotation() * 90);
 }
 
 }  // namespace media