Revert "Update legacy Tuple-using code."

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
 // and std::tuple.  The convenient MakeTuple() function takes any number of
 // 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 106 matching lines @@
 struct TupleLeaf {
   TupleLeaf() {}
   explicit TupleLeaf(typename TupleTraits<T>::ParamType x) : x(x) {}
 
   T& get() { return x; }
   const T& get() const { return x; }
 
   T x;
 };
 
+// For legacy compatibility, we name the first 8 tuple elements "a", "b", ...
+// TODO(mdempsky): Update users to use get<N>() (crbug.com/440675).
+
+#define DEFINE_TUPLE_LEAF(N, x)                                        \
+  template <typename T>                                                \
+  struct TupleLeaf<N, T> {                                             \
+    TupleLeaf() {}                                                     \
+    explicit TupleLeaf(typename TupleTraits<T>::ParamType x) : x(x) {} \
+                                                                       \
+    T& get() { return x; }                                             \
+    const T& get() const { return x; }                                 \
+                                                                       \
+    T x;                                                               \
+  }
+
+DEFINE_TUPLE_LEAF(0, a);
+DEFINE_TUPLE_LEAF(1, b);
+DEFINE_TUPLE_LEAF(2, c);
+DEFINE_TUPLE_LEAF(3, d);
+DEFINE_TUPLE_LEAF(4, e);
+DEFINE_TUPLE_LEAF(5, f);
+DEFINE_TUPLE_LEAF(6, g);
+DEFINE_TUPLE_LEAF(7, h);
+
+#undef DEFINE_TUPLE_LEAF
+
+// Deprecated compat aliases
+// TODO(mdempsky): Update users to just use Tuple instead (crbug.com/440675).
+
+using Tuple0 = Tuple<>;
+template <typename A>
+using Tuple1 = Tuple<A>;
+template <typename A, typename B>
+using Tuple2 = Tuple<A, B>;
+template <typename A, typename B, typename C>
+using Tuple3 = Tuple<A, B, C>;
+template <typename A, typename B, typename C, typename D>
+using Tuple4 = Tuple<A, B, C, D>;
+template <typename A, typename B, typename C, typename D, typename E>
+using Tuple5 = Tuple<A, B, C, D, E>;
+template <typename A,
+          typename B,
+          typename C,
+          typename D,
+          typename E,
+          typename F>
+using Tuple6 = Tuple<A, B, C, D, E, F>;
+template <typename A,
+          typename B,
+          typename C,
+          typename D,
+          typename E,
+          typename F,
+          typename G>
+using Tuple7 = Tuple<A, B, C, D, E, F, G>;
+template <typename A,
+          typename B,
+          typename C,
+          typename D,
+          typename E,
+          typename F,
+          typename G,
+          typename H>
+using Tuple8 = Tuple<A, B, C, D, E, F, G, H>;
+
 // Tuple getters --------------------------------------------------------------
 //
 // Allows accessing an arbitrary tuple element by index.
 //
 // Example usage:
 //   Tuple<int, double> t2;
 //   get<0>(t2) = 42;
 //   get<1>(t2) = 3.14;
 
 template <size_t I, typename T>
@@ skipping 134 matching lines @@
 inline void DispatchToMethod(ObjT* obj,
                              Method method,
                              const Tuple<InTs...>& in,
                              Tuple<OutTs...>* out) {
   DispatchToMethodImpl(obj, method, in, out,
                        MakeIndexSequence<sizeof...(InTs)>(),
                        MakeIndexSequence<sizeof...(OutTs)>());
 }
 
 #endif  // BASE_TUPLE_H__