[ui/ios] Add helper methods for getting the bounding size of some text.

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"
 #include "ui/ios/uikit_util.h"
 
 @implementation NSString (CrStringDrawing)
 
+- (CGRect)cr_boundingRectWithSize:(CGSize)size
+                             font:(UIFont*)font {
+  NSDictionary* attributes = font ? @{NSFontAttributeName: font} : @{};
+  return [self boundingRectWithSize:size
+                            options:NSStringDrawingUsesLineFragmentOrigin
+                         attributes:attributes
+                            context:nil];
+}
+
+- (CGSize)cr_boundingSizeWithSize:(CGSize)size
+                             font:(UIFont*)font {
+  return [self cr_boundingRectWithSize:size font:font].size;
+}
+
 - (CGSize)cr_pixelAlignedSizeWithFont:(UIFont*)font {
   DCHECK(font) << "|font| can not be nil; it is used as a NSDictionary value";
   NSDictionary* attributes = @{ NSFontAttributeName : font };
   return ui::AlignSizeToUpperPixel([self sizeWithAttributes:attributes]);
 }
 
 - (CGSize)cr_sizeWithFont:(UIFont*)font {
   if (!font)
     return CGSizeZero;
   NSDictionary* attributes = @{ NSFontAttributeName : font };
   CGSize size = [self sizeWithAttributes:attributes];
   return CGSizeMake(ceil(size.width), ceil(size.height));
 }
 
 @end