Send port disconnect events when a frame is unloaded.

chrome/common/render_messages_internal.h

Index: chrome/common/render_messages_internal.h
diff --git a/chrome/common/render_messages_internal.h b/chrome/common/render_messages_internal.h
index a1bcff21706352422e5919aa65a96a2b202b75f9..c8de0fe1d6776137a0286a9b178318d3c63669a6 100644
--- a/chrome/common/render_messages_internal.h
+++ b/chrome/common/render_messages_internal.h
@@ -1383,6 +1383,11 @@ IPC_BEGIN_MESSAGES(ViewHost)
                       int /* port_id */,
                       std::string /* message */)
 
+  // Send a message to an extension process.  The handle is the value returned
+  // by ViewHostMsg_OpenChannelToExtension.
+  IPC_MESSAGE_CONTROL1(ViewHostMsg_ExtensionCloseChannel,
+                       int /* port_id */)
+
   // Message to show a popup menu using native cocoa controls (Mac only).
   IPC_MESSAGE_ROUTED1(ViewHostMsg_ShowPopup,
                       ViewHostMsg_ShowPopup_Params)