Move logic of recording main thread scrolling reasons from cc to blink::ScrollManager

ui/events/blink/input_handler_proxy.cc

Index: ui/events/blink/input_handler_proxy.cc
diff --git a/ui/events/blink/input_handler_proxy.cc b/ui/events/blink/input_handler_proxy.cc
index 1a2e3132ccac2ddfca87af155ce3572406596152..911147a1f3711d6f2c3194c06dbe65a532754199 100644
--- a/ui/events/blink/input_handler_proxy.cc
+++ b/ui/events/blink/input_handler_proxy.cc
@@ -557,6 +557,10 @@ void InputHandlerProxy::RecordMainThreadScrollingReasons(
     return;
   }
 
+  // NonCompositedScrollReasons should only be set on the main thread.
+  DCHECK(
+      !cc::MainThreadScrollingReason::HasNonCompositedScrollReasons(reasons));
+
   // UMA_HISTOGRAM_ENUMERATION requires that the enum_max must be strictly
   // greater than the sample value. kMainThreadScrollingReasonCount doesn't
   // include the NotScrollingOnMain enum but the histograms do so adding