First step to cleanup the power-of-2 mess.

src/base/bits.cc

+// 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.
+
+#include "src/base/bits.h"
+#include "src/base/logging.h"
+
+namespace v8 {
+namespace base {
+namespace bits {
+
+uint32_t RoundUpToPowerOfTwo32(uint32_t value) {
+  DCHECK_LE(value, 0x80000000u);
+  value = value - 1;
+  value = value | (value >> 1);
+  value = value | (value >> 2);
+  value = value | (value >> 4);
+  value = value | (value >> 8);
+  value = value | (value >> 16);
+  return value + 1;
+}
+
+}  // namespace bits
+}  // namespace base
+}  // namespace v8