Package video capture skeleton as Mojo Shell Service

services/video_capture/public/interfaces/video_capture_device_factory.mojom

Index: services/video_capture/public/interfaces/video_capture_device_factory.mojom
diff --git a/services/video_capture/public/interfaces/video_capture_device_factory.mojom b/services/video_capture/public/interfaces/video_capture_device_factory.mojom
index 37bd6fc59c51b944ae2c2dcda776de38c8220391..d3cf6255b7e4d747592deb502ce45f87e164c6e1 100644
--- a/services/video_capture/public/interfaces/video_capture_device_factory.mojom
+++ b/services/video_capture/public/interfaces/video_capture_device_factory.mojom
@@ -22,7 +22,7 @@ enum VideoCaptureApi {
 };
 
 enum VideoCaptureTransportType {
-  // For AVFoundation Api, identify devices that are built-in or USB.
+  // For MACOSX_AVFOUNDATION Api, identifies devices that are built-in or USB.
   MACOSX_USB_OR_BUILT_IN,
   OTHER_TRANSPORT
 };
@@ -35,6 +35,12 @@ struct VideoCaptureDeviceDescriptor {
   VideoCaptureTransportType transport_type;
 };
 
+// Entry point for accessing video capture devices available on the machine.
+// Typical operation is to first call EnumerateDeviceDescriptors() to obtain
+// information about available devices. The obtained descriptors can then be
+// used to either obtain the supported formats of a device using
+// GetSupportedFormats(), or to create an instance of VideoCaptureDevice for
+// the device using CreateDevice().
 interface VideoCaptureDeviceFactory {
   EnumerateDeviceDescriptors()
       => (array<VideoCaptureDeviceDescriptor> descriptors);