Mojo C++ bindings: remove unnecessary getters/params of AssociatedGroup.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
@@ skipping 204 matching lines @@
         MakeRequest(&connection_ptr_, connection_ptr_task_runner_);
     connection_impl_.reset(new IntegerSenderConnectionImpl(
         std::move(connection_request), connection_binding_task_runner_,
         sender_binding_task_runner_));
 
     connection_impl_->set_get_sender_notification(
         base::Bind(&AssociatedBindTaskRunnerTest::QuitTaskRunner,
                    base::Unretained(this)));
 
     connection_ptr_->GetSender(
-        MakeRequest(&sender_ptr_, nullptr, sender_ptr_task_runner_));
+        MakeRequest(&sender_ptr_, sender_ptr_task_runner_));
     connection_binding_task_runner_->Run();
   }
 
   void QuitTaskRunner() {
     connection_binding_task_runner_->Quit();
   }
 
   base::MessageLoop loop_;
   scoped_refptr<TestTaskRunner> connection_binding_task_runner_;
   scoped_refptr<TestTaskRunner> connection_ptr_task_runner_;
@@ skipping 148 matching lines @@
   EXPECT_TRUE(sender_impl_error);
   connection_ptr_task_runner_->Run();
   EXPECT_TRUE(connection_ptr_error);
   sender_ptr_task_runner_->Run();
   EXPECT_TRUE(sender_ptr_error);
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace mojo