Drop unused base/tuple.h inclusion

net/base/test_completion_callback.h

 // Copyright (c) 2012 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 NET_BASE_TEST_COMPLETION_CALLBACK_H_
 #define NET_BASE_TEST_COMPLETION_CALLBACK_H_
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
-#include "base/tuple.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_errors.h"
 
 //-----------------------------------------------------------------------------
 // completion callback helper
 
 // A helper class for completion callbacks, designed to make it easy to run
 // tests involving asynchronous operations.  Just call WaitForResult to wait
 // for the asynchronous operation to complete.
 //
@@ skipping 117 matching lines @@
  private:
   void SetResult(int result) override;
 
   IOBuffer* buffer_;
   DISALLOW_COPY_AND_ASSIGN(ReleaseBufferCompletionCallback);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_TEST_COMPLETION_CALLBACK_H_