MacViews: Implement capture using NSEvent local+global monitors

ui/events/cocoa/events_mac.mm

Index: ui/events/cocoa/events_mac.mm
diff --git a/ui/events/cocoa/events_mac.mm b/ui/events/cocoa/events_mac.mm
index 99d391645730a79dde870c18b9a3e2606377451b..53578d5a723439d3ad56a88ae973062d3d425d7f 100644
--- a/ui/events/cocoa/events_mac.mm
+++ b/ui/events/cocoa/events_mac.mm
@@ -14,6 +14,7 @@
 #include "ui/events/cocoa/cocoa_event_utils.h"
 #include "ui/events/event_utils.h"
 #import "ui/events/keycodes/keyboard_code_conversion_mac.h"
+#import "ui/gfx/mac/coordinate_conversion.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/vector2d.h"
 
@@ -91,11 +92,11 @@ base::TimeDelta EventTimeFromNative(const base::NativeEvent& native_event) {
 
 gfx::Point EventLocationFromNative(const base::NativeEvent& native_event) {
   NSWindow* window = [native_event window];
-  if (!window) {
-    NOTIMPLEMENTED();  // Point will be in screen coordinates.
-    return gfx::Point();
-  }
   NSPoint location = [native_event locationInWindow];
+  // When the window is nil, locationInWindow gives screen coordinates.
+  if (!window)
+    return gfx::ScreenPointFromNSPoint(location);
+
   NSRect content_rect = [window contentRectForFrameRect:[window frame]];
   return gfx::Point(location.x, NSHeight(content_rect) - location.y);
 }