WIP: base::Bind for rvalue references.

base/bind_helpers.h

Index: base/bind_helpers.h
diff --git a/base/bind_helpers.h b/base/bind_helpers.h
index 24063ad1ce58fd27c5535ec81c294c597db841df..370dac8a42f299f5d4454116ee87c2b9d9420557 100644
--- a/base/bind_helpers.h
+++ b/base/bind_helpers.h
@@ -384,11 +384,31 @@ class PassedWrapper {
 
 // Unwrap the stored parameters for the wrappers above.
 template <typename T>
-struct UnwrapTraits {
+struct MoveOnlyUnwrapTraits {
+  typedef T&& ForwardType;
+  static ForwardType Unwrap(T& o) { return std::move(o); }
+};
+
+template <typename T>
+struct CopyUnwrapTraits {
   typedef const T& ForwardType;
   static ForwardType Unwrap(const T& o) { return o; }
 };
 
+// BindState<>
+template <typename T, typename U = void>
+struct UnwrapTraits : public std::conditional<base::is_move_only<T>::value,
+                                                 MoveOnlyUnwrapTraits<T>,
+                                                 CopyUnwrapTraits<T>>::type {};
+
+template <typename T>
+struct UnwrapTraits<
+    T,
+    typename std::conditional<false, typename T::value_type, void>::type>
+    : public std::conditional<base::is_move_only<typename T::value_type>::value,
+                              MoveOnlyUnwrapTraits<T>,
+                              CopyUnwrapTraits<T>>::type {};
+
 template <typename T>
 struct UnwrapTraits<UnretainedWrapper<T> > {
   typedef T* ForwardType;