[ObjC ARC] Converts ios/chrome/common:common to ARC.

ios/chrome/common/string_util.mm

 // 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.
 
 #include "ios/chrome/common/string_util.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_block.h"
-#include "base/mac/scoped_nsobject.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/sys_string_conversions.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 typedef BOOL (^ArrayFilterProcedure)(id object, NSUInteger index, BOOL* stop);
 typedef NSString* (^SubstringExtractionProcedure)(NSUInteger);
 }
 
 NSString* ParseStringWithLink(NSString* text, NSRange* out_link_range) {
   return ParseStringWithTag(text, out_link_range, @"BEGIN_LINK[ \t]*",
                             @"[ \t]*END_LINK");
 }
 
@@ skipping 18 matching lines @@
                                   options:NSRegularExpressionSearch
                                     range:range_to_search_for_end_tag];
   if (end_range.length == 0) {
     if (out_tag_range)
       *out_tag_range = tag_text_range;
     return text;
   }
 
   tag_text_range.location = after_begin_tag;
   tag_text_range.length = end_range.location - tag_text_range.location;
-  base::scoped_nsobject<NSMutableString> out_text(
-      [[NSMutableString alloc] init]);
+  NSMutableString* out_text = [[NSMutableString alloc] init];
   // First part - before the tag.
   if (begin_range.location > 0)
     [out_text appendString:[text substringToIndex:begin_range.location]];
 
   // Tag part.
   [out_text appendString:[text substringWithRange:tag_text_range]];
 
   // Last part - after the tag.
   NSUInteger after_end_tag = NSMaxRange(end_range);
   if (after_end_tag < [text length]) {
@@ skipping 40 matching lines @@
 }
 
 NSString* CleanNSStringForDisplay(NSString* dirty, BOOL removeGraphicChars) {
   NSCharacterSet* wspace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
   NSString* cleanString = dirty;
   if (removeGraphicChars) {
     cleanString = [[cleanString
         componentsSeparatedByCharactersInSet:GraphicCharactersSet()]
         componentsJoinedByString:@" "];
   }
-  base::scoped_nsobject<NSMutableArray> spaceSeparatedCompoments(
-      [[cleanString componentsSeparatedByCharactersInSet:wspace] mutableCopy]);
+  NSMutableArray* spaceSeparatedCompoments =
+      [[cleanString componentsSeparatedByCharactersInSet:wspace] mutableCopy];
   ArrayFilterProcedure filter = ^(id object, NSUInteger index, BOOL* stop) {
     return [object isEqualToString:@""];
   };
   [spaceSeparatedCompoments
       removeObjectsAtIndexes:[spaceSeparatedCompoments
                                  indexesOfObjectsPassingTest:filter]];
   cleanString = [spaceSeparatedCompoments componentsJoinedByString:@" "];
   return cleanString;
 }
 
 std::string CleanStringForDisplay(const std::string& dirty,
                                   BOOL removeGraphicChars) {
   return base::SysNSStringToUTF8(CleanNSStringForDisplay(
       base::SysUTF8ToNSString(dirty), removeGraphicChars));
 }
 
 NSString* SubstringOfWidth(NSString* string,
                            NSDictionary* attributes,
                            CGFloat targetWidth,
                            BOOL trailing) {
   if (![string length])
     return nil;
 
   UIFont* font = [attributes objectForKey:NSFontAttributeName];
   DCHECK(font);
 
   // Function to get the correct substring while insulating against
   // length overrun/underrun.
-  base::mac::ScopedBlock<SubstringExtractionProcedure> getSubstring;
+  SubstringExtractionProcedure getSubstring;
   if (trailing) {
-    getSubstring.reset([^NSString*(NSUInteger chars) {
+    getSubstring = [^NSString*(NSUInteger chars) {
       NSUInteger length = [string length];
       return [string substringFromIndex:length - MIN(length, chars)];
-    } copy]);
+    } copy];
   } else {
-    getSubstring.reset([^NSString*(NSUInteger chars) {
+    getSubstring = [^NSString*(NSUInteger chars) {
       return [string substringToIndex:MIN(chars, [string length])];
-    } copy]);
+    } copy];
   }
 
   // Guess at the number of characters that will fit, assuming
   // the font's x-height is about 25% wider than an average character (25%
   // value was determined experimentally).
   NSUInteger characters =
       MIN(targetWidth / (font.xHeight * 0.8), [string length]);
   NSInteger increment = 1;
-  NSString* substring = getSubstring.get()(characters);
+  NSString* substring = getSubstring(characters);
   CGFloat prevWidth = [substring sizeWithAttributes:attributes].width;
   do {
     characters += increment;
-    substring = getSubstring.get()(characters);
+    substring = getSubstring(characters);
     CGFloat thisWidth = [substring sizeWithAttributes:attributes].width;
     if (prevWidth > targetWidth) {
       if (thisWidth <= targetWidth)
         break;  // Shrinking the string, found the right size.
       else
         increment = -1;  // Shrink the string
     } else if (prevWidth < targetWidth) {
       if (thisWidth < targetWidth)
         increment = 1;  // Grow the string
       else {
-        substring = getSubstring.get()(characters - increment);
+        substring = getSubstring(characters - increment);
         break;  // Growing the string, found the right size.
       }
     }
     prevWidth = thisWidth;
   } while (characters > 0 && characters < [string length]);
 
   return substring;
 }