Add gfx::ToRoundedInt safe conversion method from float to int.

ui/gfx/safe_integer_conversions.cc

 // 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.
 
+#include "ui/gfx/safe_integer_conversions.h"
+
 #include <cmath>
 #include <limits>
 
 namespace gfx {
 
 int ClampToInt(float value) {
   if (value != value)
      return 0; // no int NaN.
-  if (value > std::numeric_limits<int>::max())
+  if (value >= std::numeric_limits<int>::max())
     return std::numeric_limits<int>::max();
-  if (value < std::numeric_limits<int>::min())
+  if (value <= std::numeric_limits<int>::min())
     return std::numeric_limits<int>::min();
   return static_cast<int>(value);
 }
 
 int ToFlooredInt(float value) {
   return ClampToInt(std::floor(value));
 }
 
 int ToCeiledInt(float value) {
   return ClampToInt(std::ceil(value));
 }
 
+int ToRoundedInt(float value) {
+  float rounded;
+  if (value >= 0.0f)
+    rounded = std::floor(value + 0.5f);
+  else
+    rounded = std::ceil(value - 0.5f);
+  return ClampToInt(rounded);
+}
+
 }  // namespace gfx
-