https://bugzil.la/1702919, fallback to ximage

Index: third_party/libwebrtc/modules/desktop_capture/linux/x11/x_server_pixel_buffer.cc
--- third_party/libwebrtc/modules/desktop_capture/linux/x11/x_server_pixel_buffer.cc.orig
+++ third_party/libwebrtc/modules/desktop_capture/linux/x11/x_server_pixel_buffer.cc
@@ -212,7 +212,12 @@ bool XServerPixelBuffer::Init(XAtomCache* cache, Windo
 void XServerPixelBuffer::InitShm(const XWindowAttributes& attributes) {
   Visual* default_visual = attributes.visual;
   int default_depth = attributes.depth;
-
+#if defined(__OpenBSD__)
+// pledge(2)
+  RTC_LOG(LS_WARNING) << "Unable to use shmget(2) while using pledge(2). "
+                         "Performance may be degraded.";
+  return;
+#endif
   int major, minor;
   Bool have_pixmaps;
   if (!XShmQueryVersion(display_, &major, &minor, &have_pixmaps)) {
