Remove unused include.

base/tuple.h

 // Copyright (c) 2011 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.
 
 // Use std::tuple as tuple type. This file contains helper functions for
 // working with std::tuples.
 // The functions DispatchToMethod and DispatchToFunction take a function pointer
 // or instance and method pointer, and unpack a tuple into arguments to the
 // call.
 //
@@ skipping 10 matching lines @@
 //   struct { void SomeMeth(int a, int b, int c) { } } foo;
 //   DispatchToMethod(&foo, &Foo::SomeMeth, std::make_tuple(1, 2, 3));
 //   // foo->SomeMeth(1, 2, 3);
 
 #ifndef BASE_TUPLE_H_
 #define BASE_TUPLE_H_
 
 #include <stddef.h>
 #include <tuple>
 
-#include "base/bind_helpers.h"
 #include "build/build_config.h"
 
 namespace base {
 
 // Index sequences
 //
 // Minimal clone of the similarly-named C++14 functionality.
 
 template <size_t...>
 struct IndexSequence {};
@@ skipping 149 matching lines @@
                              InTuple&& in,
                              OutTuple* out) {
   DispatchToMethodImpl(obj, method, std::forward<InTuple>(in), out,
                        MakeIndexSequenceForTuple<InTuple>(),
                        MakeIndexSequenceForTuple<OutTuple>());
 }
 
 }  // namespace base
 
 #endif  // BASE_TUPLE_H_