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

ui/ios/NSString+CrStringDrawing.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_NSSTRING_CR_STRING_DRAWING_H_
 #define UI_IOS_NSSTRING_CR_STRING_DRAWING_H_
 
 #import <UIKit/UIKit.h>
 
 @interface NSString (CrStringDrawing)
 
+// Calculates and returns the bounding rect for the receiver drawn using the
+// given size and font.
+// This method is implemented as a wrapper around
+// |boundingRectWithSize:options:attributes:context:| using the following values
+// for the parameters:
+//  - size: the provided |size|
+//  - options: NSStringDrawingUsesLineFragmentOrigin
+//  - attributes: a NSDictionary with the provided |font|
+//  - context: nil.
+//
+// Note that the rect returned may contain fractional values.
+- (CGRect)cr_boundingRectWithSize:(CGSize)size
+                             font:(UIFont*)font;
+
+// Convenience wrapper to just return the size of |boundingRectWithSize:font:|.
+//
+// Note that the size returned may contain fractional values.
+- (CGSize)cr_boundingSizeWithSize:(CGSize)size

[rohitrao (ping after 24h), 2014/11/07 14:21:26]

Do we really need this as a convenience method?  Is it ugly for callers to just
call .size on the return value of the other method?

[lliabraa, 2014/11/07 14:34:50]

We never access the origin part of the rect, so if we were to drop one of these
I'd vote for dropping the one that returns the rect.

+                             font:(UIFont*)font;
+
 // Returns the size of the string if it were to be rendered with the specified
 // font on a single line. The width and height of the CGSize returned are
 // pixel-aligned.
 //
 // This method is a convenience wrapper around sizeWithAttributes: to avoid
 // boilerplate required to put |font| in a dictionary of attributes. Do not pass
 // nil into this method.
 - (CGSize)cr_pixelAlignedSizeWithFont:(UIFont*)font;
 
 // Deprecated: Use cr_pixelAlignedSizeWithFont: or sizeWithAttributes:
 // Provides a drop-in replacement for sizeWithFont:, which was deprecated in iOS
 // 7 in favor of -sizeWithAttributes:. Specifically, this method will return
 // CGSizeZero if |font| is nil, and the width and height returned are rounded up
 // to integer values.
 // TODO(lliabraa): This method was added to ease the transition off of the
 // deprecated sizeWithFont: method. New call sites should not be added and
 // existing call sites should be audited to determine the correct behavior for
 // nil |font| and rounding, then replaced with cr_pixelAlignedSizeWithFont: or
 // sizeWithAttributes: (crbug.com/364419).
 - (CGSize)cr_sizeWithFont:(UIFont*)font;
 
 @end
 
 #endif  // UI_IOS_NSSTRING_CR_STRING_DRAWING_H_