Mark WebInputEventBuilderMacTest.ScrollWheelMatchesUIEvent flaky

content/browser/renderer_host/input/web_input_event_builders_mac_unittest.mm

Index: content/browser/renderer_host/input/web_input_event_builders_mac_unittest.mm
diff --git a/content/browser/renderer_host/input/web_input_event_builders_mac_unittest.mm b/content/browser/renderer_host/input/web_input_event_builders_mac_unittest.mm
index 45e92129e8a066ffc8f640e5fa391f228e782ae6..b92531859d9859d9b96037708eceef457841ca4e 100644
--- a/content/browser/renderer_host/input/web_input_event_builders_mac_unittest.mm
+++ b/content/browser/renderer_host/input/web_input_event_builders_mac_unittest.mm
@@ -563,9 +563,10 @@ TEST(WebInputEventBuilderMacTest, DomKeyFlagsChanged) {
   }
 }
 
+// Flaky - https://crbug.com/640457
 // Test that a ui::Event and blink::WebInputEvent made from the same NSEvent
 // have the same values for comparable fields.
-TEST(WebInputEventBuilderMacTest, ScrollWheelMatchesUIEvent) {
+TEST(WebInputEventBuilderMacTest, DISABLED_ScrollWheelMatchesUIEvent) {
   CGFloat delta_x = 123;
   CGFloat delta_y = 321;
   NSPoint location = NSMakePoint(11, 22);