Fix "unused variable" warnings.

mojo/edk/test/mojo_test_base.h

 // 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.
 
 #ifndef MOJO_EDK_TEST_MOJO_TEST_BASE_H_
 #define MOJO_EDK_TEST_MOJO_TEST_BASE_H_
 
 #include <memory>
 #include <string>
 #include <utility>
@@ skipping 26 matching lines @@
     ClientController(const std::string& client_name, MojoTestBase* test);
     ~ClientController();
 
     MojoHandle pipe() const { return pipe_.get().value(); }
 
     int WaitForShutdown();
 
    private:
     friend class MojoTestBase;
 
-    MojoTestBase* test_;
 #if !defined(OS_IOS)
     MultiprocessTestHelper helper_;
 #endif
     ScopedMessagePipeHandle pipe_;
     bool was_shutdown_ = false;
 
     DISALLOW_COPY_AND_ASSIGN(ClientController);
   };
 
   ClientController& StartClient(const std::string& client_name);
@@ skipping 158 matching lines @@
 #else  // !defined(OS_IOS)
 #define DEFINE_TEST_CLIENT_WITH_PIPE(client_name, test_base, pipe_name)
 #define DEFINE_TEST_CLIENT_TEST_WITH_PIPE(client_name, test_base, pipe_name)
 #endif  // !defined(OS_IOS)
 
 }  // namespace test
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_TEST_MOJO_TEST_BASE_H_