Remove #pragma once. Just from base/ for now.

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.
 
 // A Tuple is a generic templatized container, similar in concept to std::pair.
 // There are classes Tuple0 to Tuple6, cooresponding to the number of elements
 // it contains.  The convenient MakeTuple() function takes 0 to 6 arguments,
 // and will construct and return the appropriate Tuple object.  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 @@
 //   DispatchToFunction(&SomeFunc, tuple_a);  // SomeFunc(1, "wee")
 //   DispatchToFunction(
 //       &SomeFunc, MakeTuple(10, "foo"));    // SomeFunc(10, "foo")
 //
 //   struct { void SomeMeth(int a, int b, int c) { } } foo;
 //   DispatchToMethod(&foo, &Foo::SomeMeth, MakeTuple(1, 2, 3));
 //   // foo->SomeMeth(1, 2, 3);
 
 #ifndef BASE_TUPLE_H__
 #define BASE_TUPLE_H__
-#pragma once
 
 // Traits ----------------------------------------------------------------------
 //
 // A simple traits class for tuple arguments.
 //
 // ValueType: the bare, nonref version of a type (same as the type for nonrefs).
 // RefType: the ref version of a type (same as the type for refs).
 // ParamType: what type to pass to functions (refs should not be constified).
 
 template <class P>
@@ skipping 1001 matching lines @@
          class InA, class InB, class InC, class InD, class InE, class InF,
          class OutA, class OutB, class OutC, class OutD, class OutE>
 inline void DispatchToMethod(ObjT* obj, Method method,
                              const Tuple6<InA, InB, InC, InD, InE, InF>& in,
                              Tuple5<OutA, OutB, OutC, OutD, OutE>* out) {
   (obj->*method)(in.a, in.b, in.c, in.d, in.e, in.f,
                  &out->a, &out->b, &out->c, &out->d, &out->e);
 }
 
 #endif  // BASE_TUPLE_H__