Add a couple UIKit util functions in src/ui/ios/

ui/ios/uikit_util.mm

+// Copyright 2014 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/ios/uikit_util.h"
+
+#import <UIKit/UIKit.h>
+
+#include <cmath>
+
+namespace ui {
+
+CGFloat AlignValueToUpperPixel(CGFloat value) {
+  CGFloat scale = [[UIScreen mainScreen] scale];
+  return std::ceil(value * scale) / scale;
+}
+
+CGSize AlignSizeToUpperPixel(CGSize size) {
+  return CGSizeMake(AlignValueToUpperPixel(size.width),
+                    AlignValueToUpperPixel(size.height));
+}
+
+} // namespace ui