Mac: Add command line flag to disable AVFoundation layers

ui/base/ui_base_switches.cc

Index: ui/base/ui_base_switches.cc
diff --git a/ui/base/ui_base_switches.cc b/ui/base/ui_base_switches.cc
index 8835b658e59a641bf3cfebb7a36a924fc559bf94..2544b1a5f8eb94899573821d06e1f23d5360ba29 100644
--- a/ui/base/ui_base_switches.cc
+++ b/ui/base/ui_base_switches.cc
@@ -8,6 +8,9 @@
 namespace switches {
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
+// Disable use of AVFoundation to draw video content.
+const char kDisableAVFoundationOverlays[] = "disable-avfoundation-overlays";
+
 // Fall back to using CAOpenGLLayers display content, instead of the IOSurface
 // based overlay display path.
 const char kDisableMacOverlays[] = "disable-mac-overlays";