ExternalPopupMenu should recreate its popup only if a SELECT subtree is updated

third_party/WebKit/Source/platform/PopupMenu.h

Index: third_party/WebKit/Source/platform/PopupMenu.h
diff --git a/third_party/WebKit/Source/platform/PopupMenu.h b/third_party/WebKit/Source/platform/PopupMenu.h
index 56df30088f9a64f8e08cd477dbc78b46fca99984..9b101497d6ee495c7d820a342781c273358ac937 100644
--- a/third_party/WebKit/Source/platform/PopupMenu.h
+++ b/third_party/WebKit/Source/platform/PopupMenu.h
@@ -32,7 +32,12 @@ public:
     DEFINE_INLINE_VIRTUAL_TRACE() { }
     virtual void show() = 0;
     virtual void hide() = 0;
-    virtual void updateFromElement() = 0;
+    enum UpdateReason {
+        BySelectionChange,
+        ByStyleChange,
+        ByDOMChange,
+    };
+    virtual void updateFromElement(UpdateReason) = 0;
     virtual void disconnectClient() = 0;
 };