Use Chrome compatible naming for compiler specifics.

src/base/compiler-specific.h

+// Copyright 2014 the V8 project 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 V8_BASE_COMPILER_SPECIFIC_H_
+#define V8_BASE_COMPILER_SPECIFIC_H_
+
+#include "include/v8config.h"
+
+// Annotate a variable indicating it's ok if the variable is not used.
+// (Typically used to silence a compiler warning when the assignment
+// is important for some other reason.)
+// Use like:
+//   int x ALLOW_UNUSED = ...;
+#if V8_HAS_ATTRIBUTE_UNUSED
+#define ALLOW_UNUSED __attribute__((unused))
+#else
+#define ALLOW_UNUSED
+#endif
+
+
+// Annotate a virtual method indicating it must be overriding a virtual
+// method in the parent class.
+// Use like:
+//   virtual void bar() OVERRIDE;
+#if V8_HAS_CXX11_OVERRIDE
+#define OVERRIDE override
+#else
+#define OVERRIDE /* NOT SUPPORTED */
+#endif
+
+
+// Annotate a virtual method indicating that subclasses must not override it,
+// or annotate a class to indicate that it cannot be subclassed.
+// Use like:
+//   class B FINAL : public A {};
+//   virtual void bar() FINAL;
+#if V8_HAS_CXX11_FINAL
+#define FINAL final
+#elif V8_HAS___FINAL
+#define FINAL __final
+#elif V8_HAS_SEALED
+#define FINAL sealed
+#else
+#define FINAL /* NOT SUPPORTED */
+#endif
+
+
+// Annotate a function indicating the caller must examine the return value.
+// Use like:
+//   int foo() WARN_UNUSED_RESULT;
+#if V8_HAS_ATTRIBUTE_WARN_UNUSED_RESULT
+#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+#else
+#define WARN_UNUSED_RESULT /* NOT SUPPORTED */
+#endif
+
+#endif  // V8_BASE_COMPILER_SPECIFIC_H_