Use correct timestamp for generated mouse events on Mac.

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 79061b448a4830f99fb8958cb6b72d51a3b1ced9..b2363ee21de8d470c9c934b20061d04ad0b3592b 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1167,10 +1167,11 @@ void RenderWidgetHostViewMac::SetShowingContextMenu(bool showing) {
   // in the pipeline. Find a way to use the mouse location from the event that
   // dismissed the context menu.
   NSPoint location = [window mouseLocationOutsideOfEventStream];
+  NSTimeInterval event_time = [[NSApp currentEvent] timestamp];
   NSEvent* event = [NSEvent mouseEventWithType:NSMouseMoved
                                       location:location
                                  modifierFlags:0
-                                     timestamp:0
+                                     timestamp:event_time
                                   windowNumber:window_number()
                                        context:nil
                                    eventNumber:0