Move the logic to retrieve the WebPluginContainer to LocalFrame and Node.

third_party/WebKit/Source/core/dom/Node.h

Index: third_party/WebKit/Source/core/dom/Node.h
diff --git a/third_party/WebKit/Source/core/dom/Node.h b/third_party/WebKit/Source/core/dom/Node.h
index 93ca10f01e11fcfb497678ad3253a25bacab83cc..3bd0fcebdaf9fa947be938da13641d7e4e46ac59 100644
--- a/third_party/WebKit/Source/core/dom/Node.h
+++ b/third_party/WebKit/Source/core/dom/Node.h
@@ -74,6 +74,7 @@ using StaticNodeList = StaticNodeTypeList<Node>;
 class StyleChangeReasonForTracing;
 class Text;
 class WebMouseEvent;
+class WebPluginContainerBase;
 
 const int kNodeStyleChangeShift = 18;
 const int kNodeCustomElementShift = 20;
@@ -829,6 +830,9 @@ class CORE_EXPORT Node : public EventTarget {
     CheckSlotChange(SlotChangeType::kInitial);
   }
 
+  // If the node is a plugin, then this returns its WebPluginContainerBase.
+  WebPluginContainerBase* GetWebPluginContainerBase() const;
+
   DECLARE_VIRTUAL_TRACE();
 
   DECLARE_VIRTUAL_TRACE_WRAPPERS();