Bring the feedback button to the Mac sad tab

base/template_util.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.
 
 #ifndef BASE_TEMPLATE_UTIL_H_
 #define BASE_TEMPLATE_UTIL_H_
 
 #include <stddef.h>
 #include <iosfwd>
 #include <type_traits>
@@ skipping 11 matching lines @@
      __GLIBCXX__ == CR_GLIBCXX_4_6_4)
 #define CR_USE_FALLBACKS_FOR_OLD_GLIBCXX
 #endif
 
 namespace base {
 
 template <class T> struct is_non_const_reference : std::false_type {};
 template <class T> struct is_non_const_reference<T&> : std::true_type {};
 template <class T> struct is_non_const_reference<const T&> : std::false_type {};
 
+// underlying_number
+// Casts an enum to its underlying integral type, leaves other numbers alone.
+// Useful for scoped enums, which don't cast implicitly.
+template <typename T,
+          typename std::enable_if<std::is_enum<T>::value, int>::type = 0>
+constexpr typename std::underlying_type<T>::type underlying_number(T val) {
+  return static_cast<typename std::underlying_type<T>::type>(val);
+}
+template <typename T,
+          typename std::enable_if<std::is_arithmetic<T>::value, int>::type = 0>
+constexpr T underlying_number(T val) {
+  return val;
+}
+
 // is_assignable
 
 namespace internal {
 
 template <typename First, typename Second>
 struct SelectSecond {
   using type = Second;
 };
 
 struct Any {
@@ skipping 82 matching lines @@
 #else
 template <class T>
 using is_trivially_destructible = std::is_trivially_destructible<T>;
 #endif
 
 }  // namespace base
 
 #undef CR_USE_FALLBACKS_FOR_OLD_GLIBCXX
 
 #endif  // BASE_TEMPLATE_UTIL_H_