Revert "Update legacy Tuple-using code."

base/tuple.h

Index: base/tuple.h
diff --git a/base/tuple.h b/base/tuple.h
index 4408074335b3bd2c28b5ee5719a0b63ba262971c..a0d22454abde023b5fe298d52ac78127c6cd2d2b 100644
--- a/base/tuple.h
+++ b/base/tuple.h
@@ -124,6 +124,71 @@ struct TupleLeaf {
   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.