1 files changed, 129 insertions, 1 deletions
diff --git a/third_party/chromium/base/callback_internal.h b/third_party/chromium/base/callback_internal.h
index d700794..3682bf9 100644
--- a/third_party/chromium/base/callback_internal.h
+++ b/third_party/chromium/base/callback_internal.h
@@ -8,12 +8,17 @@
 #ifndef BASE_CALLBACK_INTERNAL_H_
 #define BASE_CALLBACK_INTERNAL_H_
 
-#include <atomic>
+#include <stddef.h>
+#include <map>
+#include <memory>
+#include <type_traits>
+#include <vector>
 
 #include "base/base_export.h"
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 
 namespace base {
 namespace internal {
@@ -112,6 +117,129 @@ class BASE_EXPORT CallbackBase<CopyMode::Copyable>
 extern template class CallbackBase<CopyMode::MoveOnly>;
 extern template class CallbackBase<CopyMode::Copyable>;
 
+// A helper template to determine if given type is non-const move-only-type,
+// i.e. if a value of the given type should be passed via std::move() in a
+// destructive way. Types are considered to be move-only if they have a
+// sentinel MoveOnlyTypeForCPP03 member: a class typically gets this from using
+// the DISALLOW_COPY_AND_ASSIGN_WITH_MOVE_FOR_BIND macro.
+// It would be easy to generalize this trait to all move-only types... but this
+// confuses template deduction in VS2013 with certain types such as
+// std::unique_ptr.
+// TODO(dcheng): Revisit this when Windows switches to VS2015 by default.
+
+template <typename T> struct IsMoveOnlyType {
+  // Types YesType and NoType are guaranteed such that sizeof(YesType) <
+  // sizeof(NoType).
+  using YesType = char;
+  struct NoType { YesType dummy[2]; };
+
+  template <typename U>
+  static YesType Test(const typename U::MoveOnlyTypeForCPP03*);
+
+  template <typename U>
+  static NoType Test(...);
+
+  static const bool value = sizeof((Test<T>(0))) == sizeof(YesType) &&
+                            !std::is_const<T>::value;
+};
+
+// Specialization of IsMoveOnlyType so that std::unique_ptr is still considered
+// move-only, even without the sentinel member.
+template <typename T, typename D>
+struct IsMoveOnlyType<std::unique_ptr<T, D>> : std::true_type {};
+
+// Specialization of std::vector, so that it's considered move-only if the
+// element type is move-only. Allocator is explicitly ignored when determining
+// move-only status of the std::vector.
+template <typename T, typename Allocator>
+struct IsMoveOnlyType<std::vector<T, Allocator>> : IsMoveOnlyType<T> {};
+
+template <typename>
+struct CallbackParamTraitsForMoveOnlyType;
+
+template <typename>
+struct CallbackParamTraitsForNonMoveOnlyType;
+
+// TODO(tzik): Use a default parameter once MSVS supports variadic templates
+// with default values.
+// http://connect.microsoft.com/VisualStudio/feedbackdetail/view/957801/compilation-error-with-variadic-templates
+//
+// This is a typetraits object that's used to take an argument type, and
+// extract a suitable type for forwarding arguments.
+template <typename T>
+struct CallbackParamTraits
+    : std::conditional<IsMoveOnlyType<T>::value,
+         CallbackParamTraitsForMoveOnlyType<T>,
+         CallbackParamTraitsForNonMoveOnlyType<T>>::type {
+};
+
+template <typename T>
+struct CallbackParamTraitsForNonMoveOnlyType {
+  using ForwardType = const T&;
+};
+
+// Note that for array types, we implicitly add a const in the conversion. This
+// means that it is not possible to bind array arguments to functions that take
+// a non-const pointer. Trying to specialize the template based on a "const
+// T[n]" does not seem to match correctly, so we are stuck with this
+// restriction.
+template <typename T, size_t n>
+struct CallbackParamTraitsForNonMoveOnlyType<T[n]> {
+  using ForwardType = const T*;
+};
+
+// See comment for CallbackParamTraits<T[n]>.
+template <typename T>
+struct CallbackParamTraitsForNonMoveOnlyType<T[]> {
+  using ForwardType = const T*;
+};
+
+// Parameter traits for movable-but-not-copyable scopers.
+//
+// Callback<>/Bind() understands movable-but-not-copyable semantics where
+// the type cannot be copied but can still have its state destructively
+// transferred (aka. moved) to another instance of the same type by calling a
+// helper function.  When used with Bind(), this signifies transferal of the
+// object's state to the target function.
+//
+// For these types, the ForwardType must not be a const reference, or a
+// reference.  A const reference is inappropriate, and would break const
+// correctness, because we are implementing a destructive move.  A non-const
+// reference cannot be used with temporaries which means the result of a
+// function or a cast would not be usable with Callback<> or Bind().
+template <typename T>
+struct CallbackParamTraitsForMoveOnlyType {
+  using ForwardType = T;
+};
+
+// CallbackForward() is a very limited simulation of C++11's std::forward()
+// used by the Callback/Bind system for a set of movable-but-not-copyable
+// types.  It is needed because forwarding a movable-but-not-copyable
+// argument to another function requires us to invoke the proper move
+// operator to create a rvalue version of the type.  The supported types are
+// whitelisted below as overloads of the CallbackForward() function. The
+// default template compiles out to be a no-op.
+//
+// In C++11, std::forward would replace all uses of this function.  However, it
+// is impossible to implement a general std::forward without C++11 due to a lack
+// of rvalue references.
+//
+// In addition to Callback/Bind, this is used by PostTaskAndReplyWithResult to
+// simulate std::forward() and forward the result of one Callback as a
+// parameter to another callback. This is to support Callbacks that return
+// the movable-but-not-copyable types whitelisted above.
+template <typename T>
+typename std::enable_if<!IsMoveOnlyType<T>::value, T>::type& CallbackForward(
+    T& t) {
+  return t;
+}
+
+template <typename T>
+typename std::enable_if<IsMoveOnlyType<T>::value, T>::type CallbackForward(
+    T& t) {
+  return std::move(t);
+}
+
 }  // namespace internal
 }  // namespace base