Add WTF::MakeUnique to mirror C++14's std::make_unique.

third_party/WebKit/Source/wtf/PtrUtil.h

Index: third_party/WebKit/Source/wtf/PtrUtil.h
diff --git a/third_party/WebKit/Source/wtf/PtrUtil.h b/third_party/WebKit/Source/wtf/PtrUtil.h
index a26aa4cfe2e67008cc175e83c97cbe0fab630051..bba00bbc207591196335ed16fbdd699472eeecba 100644
--- a/third_party/WebKit/Source/wtf/PtrUtil.h
+++ b/third_party/WebKit/Source/wtf/PtrUtil.h
@@ -5,6 +5,7 @@
 #ifndef PtrUtil_h
 #define PtrUtil_h
 
+#include "base/memory/ptr_util.h"
 #include "wtf/TypeTraits.h"
 
 #include <memory>
@@ -27,8 +28,27 @@ std::unique_ptr<T[]> wrapArrayUnique(T* ptr) {
   return std::unique_ptr<T[]>(ptr);
 }
 
+// WTF::makeUnique is base::MakeUnique. See base/ptr_util.h for documentation.
+template <typename T, typename... Args>
+auto makeUnique(Args&&... args)
+    -> decltype(base::MakeUnique<T>(std::forward<Args>(args)...)) {
+  static_assert(
+      !WTF::IsGarbageCollectedType<T>::value,
+      "Garbage collected types should not be stored in std::unique_ptr!");
+  return base::MakeUnique<T>(std::forward<Args>(args)...);
+}
+
+template <typename T>
+auto makeUnique(size_t size) -> decltype(base::MakeUnique<T>(size)) {
+  static_assert(
+      !WTF::IsGarbageCollectedType<T>::value,
+      "Garbage collected types should not be stored in std::unique_ptr!");
+  return base::MakeUnique<T>(size);
+}
+
 }  // namespace WTF
 
+using WTF::makeUnique;
 using WTF::wrapUnique;
 using WTF::wrapArrayUnique;