Upstream string_util function.

ios/chrome/common/string_util.h

+// Copyright 2013 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 IOS_CHROME_COMMON_STRING_UTIL_H_
+#define IOS_CHROME_COMMON_STRING_UTIL_H_
+
+#import <CoreGraphics/CoreGraphics.h>
+#import <Foundation/Foundation.h>
+#include <string>
+
+// Parses a string with an embedded link inside, delineated by BEGIN_LINK and
+// END_LINK. Returns the string without the link delimiters. If |out_link_range|
+// is not null, then it is filled out with the range of the link in the returned
+// string.
+// If no link is found, then it returns |text| and sets |out_link_range| to
+// {NSNotFound, 0}.
+NSString* ParseStringWithLink(NSString* text, NSRange* out_link_range);
+
+// Utility method that returns an NSCharacterSet containing Unicode graphics
+// and drawing characters (but not including the Braille Patterns characters).
+NSCharacterSet* GraphicCharactersSet();
+
+// Cleans an NSString by collapsing whitespace and (if |trim| is true)
+// removing leading and trailing spaces. If |removeGraphicChars| is true,
+// unicode graphic characters will also be removed from the string.
+NSString* CleanNSStringForDisplay(NSString* dirty,
+                                  BOOL removeGraphicChars,
+                                  BOOL trim);
+
+// Cleans a std::string identically to CleanNSStringForDisplay()
+std::string CleanStringForDisplay(std::string dirty,
+                                  BOOL removeGraphicChars,
+                                  BOOL trim);
+
+// Find the longest leading substring of |string| that, when rendered with
+// |attributes|, will fit on a single line inside |targetWidth|. If |trailing|
+// is YES, then find the trailing (instead of leading) substring.
+NSString* SubstringOfWidth(NSString* string,
+                           NSDictionary* attributes,
+                           CGFloat targetWidth,
+                           BOOL trailing);
+
+#endif  // IOS_CHROME_COMMON_STRING_UTIL_H_