MouseWheelEventManager is added to handle wheel events.

third_party/WebKit/Source/core/input/EventHandlingUtil.cpp

Index: third_party/WebKit/Source/core/input/EventHandlingUtil.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandlingUtil.cpp b/third_party/WebKit/Source/core/input/EventHandlingUtil.cpp
index 2ae4665c82a002a4953cdc4729abd10cddf36626..661b39342fa8e068b59417dc3d6fc0b513ab0791 100644
--- a/third_party/WebKit/Source/core/input/EventHandlingUtil.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandlingUtil.cpp
@@ -6,6 +6,7 @@
 
 #include "core/frame/LocalFrame.h"
 #include "core/frame/LocalFrameView.h"
+#include "core/layout/LayoutEmbeddedContent.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/paint/PaintLayer.h"
 #include "platform/scroll/ScrollableArea.h"
@@ -128,5 +129,21 @@ MouseEventWithHitTestResults PerformMouseEventHitTest(
       mev);
 }
 
+LocalFrame* SubframeForTargetNode(Node* node) {
+  if (!node)
+    return nullptr;
+
+  LayoutObject* layout_object = node->GetLayoutObject();
+  if (!layout_object || !layout_object->IsLayoutEmbeddedContent())
+    return nullptr;
+
+  LocalFrameView* frame_view =
+      ToLayoutEmbeddedContent(layout_object)->ChildFrameView();
+  if (!frame_view)
+    return nullptr;
+
+  return &frame_view->GetFrame();
+}
+
 }  // namespace EventHandlingUtil
 }  // namespace blink