Disable call to xpc_connection_set_oneshot_instance

https://bugs.webkit.org/show_bug.cgi?id=267368
rdar://120806906

Reviewed by Brent Fulgham.

Disable call to xpc_connection_set_oneshot_instance when launching WebKit processes
as extensions, since this call is not needed, then.

* Source/WebKit/UIProcess/Launcher/cocoa/ProcessLauncherCocoa.mm:
(WebKit::ProcessLauncher::launchProcess):
(WebKit::ProcessLauncher::finishLaunchingProcess):

Canonical link: https://commits.webkit.org/273043@main

Source/WebKit/UIProcess/Launcher/cocoa/ProcessLauncherCocoa.mm

@@ -188,6 +188,10 @@ static void launchWithExtensionKit(ProcessLauncher& processLauncher, ProcessLaun
 
             launcher->m_xpcConnection = WTFMove(xpcConnection);
             launcher->m_process = WTFMove(process);
+            if (!launcher->m_xpcConnection) {
+                NSLog(@"Failed to create XPC connection, error = %@", error);
+                return;
+            }
             launcher->finishLaunchingProcess(name.characters());
         });
     };
@@ -207,7 +211,9 @@ static void launchWithExtensionKit(ProcessLauncher& processLauncher, ProcessLaun
     uuid_t uuid;
     uuid_generate(uuid);
 
+#if !USE(EXTENSIONKIT)
     xpc_connection_set_oneshot_instance(m_xpcConnection.get(), uuid);
+#endif
 
     // Inherit UI process localization. It can be different from child process default localization:
     // 1. When the application and system frameworks simply have different localized resources available, we should match the application.