diff --git hwnd_message_handler.cc hwnd_message_handler.cc
index bd2072b..c3fd2ea 100644
--- hwnd_message_handler.cc
+++ hwnd_message_handler.cc
@@ -2649,8 +2649,12 @@ LRESULT HWNDMessageHandler::HandleMouseEventInternal(UINT message,
             "440919 HWNDMessageHandler::HandleMouseEventInternal6"));
 
     // Reroute the mouse wheel to the window under the pointer if applicable.
-    return (ui::RerouteMouseWheel(hwnd(), w_param, l_param) ||
-            delegate_->HandleMouseEvent(ui::MouseWheelEvent(msg))) ? 0 : 1;
+    if (ui::RerouteMouseWheel(hwnd(), w_param, l_param) ||
+        delegate_->HandleMouseEvent(ui::MouseWheelEvent(msg))) {
+      SetMsgHandled(TRUE);
+      return 0;
+    }
+    return 1;
   }
 
   // TODO(vadimt): Remove ScopedTracker below once crbug.com/440919 is fixed.