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

mojo/public/cpp/bindings/tests/sync_method_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 <utility>
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 251 matching lines @@
 
 class SyncMethodAssociatedTest : public SyncMethodTest {
  public:
   SyncMethodAssociatedTest() {}
   ~SyncMethodAssociatedTest() override {}
 
  protected:
   void SetUp() override {
     master_impl_.reset(new TestSyncMasterImpl(MakeRequest(&master_ptr_)));
 
-    master_ptr_.associated_group()->CreateAssociatedInterface(
-        AssociatedGroup::WILL_PASS_REQUEST, &asso_ptr_info_, &asso_request_);
-    master_ptr_.associated_group()->CreateAssociatedInterface(
-        AssociatedGroup::WILL_PASS_PTR, &opposite_asso_ptr_info_,
-        &opposite_asso_request_);
+    asso_request_ = MakeRequest(&asso_ptr_info_);
+    opposite_asso_request_ = MakeRequest(&opposite_asso_ptr_info_);
 
     master_impl_->set_send_interface_handler(
         [this](TestSyncAssociatedPtrInfo ptr) {
           opposite_asso_ptr_info_ = std::move(ptr);
         });
     base::RunLoop run_loop;
     master_impl_->set_send_request_handler(
         [this, &run_loop](TestSyncAssociatedRequest request) {
           asso_request_ = std::move(request);
           run_loop.Quit();
@@ skipping 446 matching lines @@
   int32_t result_value = -1;
   ASSERT_TRUE(master_ptr_->Echo(456, &result_value));
   EXPECT_EQ(456, result_value);
 }
 
 // TODO(yzshen): Add more tests related to associated interfaces.
 
 }  // namespace
 }  // namespace test
 }  // namespace mojo