Mojo C++ bindings: remove some usage of AssociatedGroup from user code.

mojo/public/cpp/bindings/tests/bind_task_runner_unittest.cc

Index: mojo/public/cpp/bindings/tests/bind_task_runner_unittest.cc
diff --git a/mojo/public/cpp/bindings/tests/bind_task_runner_unittest.cc b/mojo/public/cpp/bindings/tests/bind_task_runner_unittest.cc
index aa4dac761f61e65f3145ee0503a3b4f43ea1095b..7a1512baa729efc5f8bb185fed08e3774078f2e5 100644
--- a/mojo/public/cpp/bindings/tests/bind_task_runner_unittest.cc
+++ b/mojo/public/cpp/bindings/tests/bind_task_runner_unittest.cc
@@ -10,7 +10,6 @@
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "mojo/public/cpp/bindings/associated_binding.h"
-#include "mojo/public/cpp/bindings/associated_group.h"
 #include "mojo/public/cpp/bindings/associated_interface_ptr.h"
 #include "mojo/public/cpp/bindings/associated_interface_ptr_info.h"
 #include "mojo/public/cpp/bindings/associated_interface_request.h"
@@ -222,9 +221,8 @@ class AssociatedBindTaskRunnerTest : public testing::Test {
         base::Bind(&AssociatedBindTaskRunnerTest::QuitTaskRunner,
                    base::Unretained(this)));
 
-    connection_ptr_->GetSender(MakeRequest(&sender_ptr_,
-                                           connection_ptr_.associated_group(),
-                                           sender_ptr_task_runner_));
+    connection_ptr_->GetSender(
+        MakeRequest(&sender_ptr_, nullptr, sender_ptr_task_runner_));
     connection_binding_task_runner_->Run();
   }