Support for move-only types in SmallMap.

base/memory/manual_constructor.h

 // Copyright (c) 2012 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.
 
 // ManualConstructor statically-allocates space in which to store some
 // object, but does not initialize it.  You can then call the constructor
 // and destructor for the object yourself as you see fit.  This is useful
 // for memory management optimizations, where you want to initialize and
 // destroy an object multiple times but only allocate it once.
 //
@@ skipping 36 matching lines @@
     return space_.template data_as<Type>();
   }
 
   inline Type* operator->() { return get(); }
   inline const Type* operator->() const { return get(); }
 
   inline Type& operator*() { return *get(); }
   inline const Type& operator*() const { return *get(); }
 
   template <typename... Ts>
-  inline void Init(const Ts&... params) {
-    new(space_.void_data()) Type(params...);
+  inline void Init(Ts&&... params) {
+    new(space_.void_data()) Type(std::forward<Ts>(params)...);
+  }
+
+  inline void Move(ManualConstructor<Type>&& o) {

[danakj, 2016/02/27 00:32:02]

std::move() means you're moving the object, this is a member function and you're
initializing the object, by moving the parameter..

Can we name it InitFromMove()?

[btolsch, 2016/02/27 01:18:37]

Done.

+    Init(std::move(*o));
   }
 
   inline void Destroy() {
     get()->~Type();
   }
 
  private:
   AlignedMemory<sizeof(Type), ALIGNOF(Type)> space_;
 };
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_MANUAL_CONSTRUCTOR_H_