[Video Capture Service] Fix for VideoFacing constraint not working

The struct media::VideoCaptureDeviceDescriptor contains a field for facing_mode.
The corresponding mojo struct does not contain this field. Because of it, the
information will be dropped when crossing a Mojo boundary, i.e. when the video
capture service is used.

Bug: 829114
Change-Id: I8193c3db125450e80dd9f30b7babee3063013ef9
Reviewed-on: https://chromium-review.googlesource.com/1140956Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Christian Fremerey <chfremer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575840}

media/capture/mojom/video_capture_types.mojom

@@ -50,6 +50,12 @@ enum PowerLineFrequency {
   HZ_60
 };
 
+enum VideoFacingMode {
+  NONE,
+  USER,
+  ENVIRONMENT
+};
+
 enum VideoCaptureApi {
   LINUX_V4L2_SINGLE_PLANE,
   WIN_MEDIA_FOUNDATION,
@@ -115,6 +121,7 @@ struct VideoCaptureDeviceDescriptor {
   string display_name;
   string device_id;
   string model_id;
+  VideoFacingMode facing_mode;
   VideoCaptureApi capture_api;
   VideoCaptureTransportType transport_type;
   VideoCaptureDeviceDescriptorCameraCalibration? camera_calibration;

media/capture/mojom/video_capture_types_mojom_traits.cc

@@ -273,6 +273,44 @@ bool EnumTraits<media::mojom::VideoCaptureBufferType,
   return false;
 }
 
+// static
+media::mojom::VideoFacingMode
+EnumTraits<media::mojom::VideoFacingMode, media::VideoFacingMode>::ToMojom(
+    media::VideoFacingMode input) {
+  switch (input) {
+    case media::VideoFacingMode::MEDIA_VIDEO_FACING_NONE:
+      return media::mojom::VideoFacingMode::NONE;
+    case media::VideoFacingMode::MEDIA_VIDEO_FACING_USER:
+      return media::mojom::VideoFacingMode::USER;
+    case media::VideoFacingMode::MEDIA_VIDEO_FACING_ENVIRONMENT:
+      return media::mojom::VideoFacingMode::ENVIRONMENT;
+    case media::VideoFacingMode::NUM_MEDIA_VIDEO_FACING_MODES:
+      NOTREACHED();
+      return media::mojom::VideoFacingMode::NONE;
+  }
+  NOTREACHED();
+  return media::mojom::VideoFacingMode::NONE;
+}
+
+// static
+bool EnumTraits<media::mojom::VideoFacingMode, media::VideoFacingMode>::
+    FromMojom(media::mojom::VideoFacingMode input,
+              media::VideoFacingMode* output) {
+  switch (input) {
+    case media::mojom::VideoFacingMode::NONE:
+      *output = media::VideoFacingMode::MEDIA_VIDEO_FACING_NONE;
+      return true;
+    case media::mojom::VideoFacingMode::USER:
+      *output = media::VideoFacingMode::MEDIA_VIDEO_FACING_USER;
+      return true;
+    case media::mojom::VideoFacingMode::ENVIRONMENT:
+      *output = media::VideoFacingMode::MEDIA_VIDEO_FACING_ENVIRONMENT;
+      return true;
+  }
+  NOTREACHED();
+  return false;
+}
+
 // static
 media::mojom::VideoCaptureApi
 EnumTraits<media::mojom::VideoCaptureApi, media::VideoCaptureApi>::ToMojom(
@@ -441,6 +479,8 @@ bool StructTraits<media::mojom::VideoCaptureDeviceDescriptorDataView,
     return false;
   if (!data.ReadModelId(&(output->model_id)))
     return false;
+  if (!data.ReadFacingMode(&(output->facing)))
+    return false;
   if (!data.ReadCaptureApi(&(output->capture_api)))
     return false;
   if (!data.ReadTransportType(&(output->transport_type)))

media/capture/mojom/video_capture_types_mojom_traits.h

@@ -5,6 +5,7 @@
 #ifndef MEDIA_CAPTURE_MOJOM_VIDEO_CAPTURE_TYPES_MOJOM_TRAITS_H_
 #define MEDIA_CAPTURE_MOJOM_VIDEO_CAPTURE_TYPES_MOJOM_TRAITS_H_
 
+#include "media/base/video_facing.h"
 #include "media/capture/mojom/video_capture_types.mojom.h"
 #include "media/capture/video/video_capture_device_descriptor.h"
 #include "media/capture/video/video_capture_device_info.h"
@@ -50,6 +51,13 @@ struct EnumTraits<media::mojom::VideoCaptureBufferType,
                         media::VideoCaptureBufferType* out);
 };
 
+template <>
+struct EnumTraits<media::mojom::VideoFacingMode, media::VideoFacingMode> {
+  static media::mojom::VideoFacingMode ToMojom(media::VideoFacingMode input);
+  static bool FromMojom(media::mojom::VideoFacingMode input,
+                        media::VideoFacingMode* output);
+};
+
 template <>
 struct EnumTraits<media::mojom::VideoCaptureApi, media::VideoCaptureApi> {
   static media::mojom::VideoCaptureApi ToMojom(media::VideoCaptureApi input);
@@ -160,6 +168,11 @@ struct StructTraits<media::mojom::VideoCaptureDeviceDescriptorDataView,
     return input.model_id;
   }
 
+  static media::VideoFacingMode facing_mode(
+      const media::VideoCaptureDeviceDescriptor& input) {
+    return input.facing;
+  }
+
   static media::VideoCaptureApi capture_api(
       const media::VideoCaptureDeviceDescriptor& input) {
     return input.capture_api;