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

ui/ios/uikit_util.h

+// 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.
+
+#ifndef UI_IOS_UIKIT_UTIL_H_
+#define UI_IOS_UIKIT_UTIL_H_
+
+#import <UIKit/UIKit.h>
+
+// UI Util containing functions that require UIKit.
+
+namespace ui {
+
+// Returns the closest pixel-aligned value higher than |value|, taking the scale
+// factor into account. At a scale of 1, equivalent to ceil().
+CGFloat alignValueToUpperPixel(CGFloat value);

[stuartmorgan, 2014/09/04 22:16:10]

s/align/Align/ (same below).

I also wonder if we should call it AlignedValueAtUpperPixel (similarly below) so
that nobody writes this bug:
  // get a value
  AlignValueToUpperPixel(value);
  // |value| is aligned now, right?

[lliabraa, 2014/09/05 16:53:44]

Done.
I see your point, but this type of method signature seems fairly common, e.g.
ceil. I've dropped the "Value" and "Size" from the method names so at least the
parameter name is no longer in the method name. Do you think that helps?

Another alternative would be GetValueAlignedToUpperPixel();
GetSizeAlignedToUpperPixel().

+
+// Returns the size resulting from applying alignValueToUpperPixel to both
+// components.
+CGSize alignSizeToUpperPixel(CGSize size);
+
+} // namespace ui
+
+#endif  // UI_IOS_UIKIT_UTIL_H_