Pass camera facing to WebKit

media/capture/video_capture_types.h

Index: media/capture/video_capture_types.h
diff --git a/media/capture/video_capture_types.h b/media/capture/video_capture_types.h
index 7a6246beaf6cd2af413654378a8a60475302feff..c8e3c2cc80d765e564b96c8e0c17c83eb3ac42e6 100644
--- a/media/capture/video_capture_types.h
+++ b/media/capture/video_capture_types.h
@@ -28,6 +28,13 @@ enum VideoPixelStorage {
   PIXEL_STORAGE_MAX = PIXEL_STORAGE_CPU,
 };
 
+enum class CameraFacing {
+  DEFAULT = 0,
+  // FRONT means a person's right will be on the left in the video.

[wuchengli, 2017/01/09 08:28:00]

This is not always true. Apps can choose not to mirror the video. To be
consistent, we can follow mediacapture spec. FRONT means "The camera is facing
toward the user (a self-view camera)."

https://www.w3.org/TR/mediacapture-streams/#idl-def-VideoFacingModeEnum.user

[shenghao, 2017/01/10 12:16:35]

Done.

+  FRONT,

[wuchengli, 2017/01/09 08:28:00]

Also document BACK.

// The source is facing away from the user (viewing the environment).

[shenghao, 2017/01/10 12:16:35]

Done.

+  BACK,
+};
+
 // Policies for capture devices that have source content that varies in size.
 // It is up to the implementation how the captured content will be transformed
 // (e.g., scaling and/or letterboxing) in order to produce video frames that