Index: content/browser/media/capture/web_contents_video_capture_device.h |
diff --git a/content/browser/media/capture/web_contents_video_capture_device.h b/content/browser/media/capture/web_contents_video_capture_device.h |
index ab81c35405593e7329d2865421a7ab444de4a5c2..0446175978a15cce3161e1d65eacf79033ebcfc6 100644 |
--- a/content/browser/media/capture/web_contents_video_capture_device.h |
+++ b/content/browser/media/capture/web_contents_video_capture_device.h |
@@ -15,9 +15,15 @@ |
namespace content { |
-// A virtualized VideoCaptureDevice that mirrors the displayed contents of a |
+// A virtualized VideoCaptureDevice that captures the displayed contents of a |
// WebContents (i.e., the composition of an entire render frame tree), producing |
-// a stream of video frames. |
+// a stream of video frames. As such, WebContentsVideoCaptureDevice is only |
+// supported on platforms that use the Chromium compositor, have a |
+// content::RenderWidgetHostView implementation that supports frame subscription |
+// (via BeginFrameSubscription()), and can perform read-back into |
+// media::VideoFrames (i.e., |
+// RenderWidgetHostViewBase::CopyFromCompositingSurfaceToVideoFrame() is |
+// functional). |
// |
// An instance is created by providing a device_id. The device_id contains |
// information necessary for finding a WebContents instance. From then on, |