Add NSString category for providing iOS6-style string drawing APIs.

ui/ios/NSString+CrStringDrawing.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.
+
+#import "ui/ios/NSString+CrStringDrawing.h"
+
+#include "base/logging.h"
+
+@implementation NSString (CrStringDrawing)
+
+- (CGSize)cr_sizeWithFont:(UIFont*)font {

[stuartmorgan, 2014/08/28 15:18:14]

It's not really clear to me why
  [foo sizeWithAttributes:@{ NSFontAttributeName : font }]
is enough worse than this to warrant a utility method. It's not actually more
brittle since the utility doesn't handle nil, and it's barely more verbose. Is
this extremely common or something?

[lliabraa, 2014/08/28 19:25:06]

As discussed offline, this category should have a method to do pixel-aligning
and dictionary construction and a method to serve as a drop-in replacement for
existing call sites.

+  DCHECK(font) << "|font| can not be nil; it is used as a NSDictionary value";
+  NSDictionary* attributes = @{ NSFontAttributeName : font };
+  return [self sizeWithAttributes:attributes];
+}
+
+- (CGSize)cr_integralSizeWithFont:(UIFont*)font {
+  if (!font)
+    return CGSizeZero;
+  CGSize size = [self cr_sizeWithFont:font];
+  return CGSizeMake(ceil(size.width), ceil(size.height));
+}
+
+@end