[Extensions] Remove source/opener tab id from extension ports

chrome/browser/extensions/api/messaging/extension_message_port.h

Index: chrome/browser/extensions/api/messaging/extension_message_port.h
diff --git a/chrome/browser/extensions/api/messaging/extension_message_port.h b/chrome/browser/extensions/api/messaging/extension_message_port.h
index 92b785803d2184935a5558c0dfaf4921d6644757..af122c0bacaf83fb5a07e5f4385f39cc0103c8a7 100644
--- a/chrome/browser/extensions/api/messaging/extension_message_port.h
+++ b/chrome/browser/extensions/api/messaging/extension_message_port.h
@@ -98,11 +98,6 @@ class ExtensionMessagePort : public MessageService::MessagePort {
   // when the frame is removed or unloaded.
   std::set<content::RenderFrameHost*> frames_;
 
-  // The ID of the tab where the channel was created. This is saved so that any
-  // onMessage events can be run in the scope of the tab.
-  // Only set on receiver ports (if the opener was a tab). -1 if invalid.
-  int opener_tab_id_;
-
   // Whether the renderer acknowledged creation of the port. This is used to
   // distinguish abnormal port closure (e.g. no receivers) from explicit port
   // closure (e.g. by the port.disconnect() JavaScript method in the renderer).