Use SysNSStringToUTF8 instead of UTF8String in recent clipboard.

components/open_from_clipboard/clipboard_recent_content_ios.mm

 // Copyright 2015 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 "components/open_from_clipboard/clipboard_recent_content_ios.h"
 
 #import <CommonCrypto/CommonDigest.h>
 #include <stddef.h>
 #include <stdint.h>
 #import <UIKit/UIKit.h>
@@ skipping 80 matching lines @@
     url::kDataScheme,
     url::kAboutScheme,
 };
 
 // Compute a hash consisting of the first 4 bytes of the MD5 hash of |string|.
 // This value is used to detect pasteboard content change. Keeping only 4 bytes
 // is a privacy requirement to introduce collision and allow deniability of
 // having copied a given string.
 NSData* WeakMD5FromNSString(NSString* string) {
   unsigned char hash[CC_MD5_DIGEST_LENGTH];
-  const char* c_string = [string UTF8String];
+  const std::string clipboard = base::SysNSStringToUTF8(string);
+  const char* c_string = clipboard.c_str();
   CC_MD5(c_string, strlen(c_string), hash);
   NSData* data = [NSData dataWithBytes:hash length:4];
   return data;
 }
 
 }  // namespace
 
 bool ClipboardRecentContentIOS::GetRecentURLFromClipboard(GURL* url) {
   DCHECK(url);
   UpdateIfNeeded();
@@ skipping 125 matching lines @@
                              forKey:kPasteboardChangeCountKey];
   [shared_user_defaults_ setObject:last_pasteboard_change_date_
                             forKey:kPasteboardChangeDateKey];
   [shared_user_defaults_ setObject:last_pasteboard_entry_md5_
                             forKey:kPasteboardEntryMD5Key];
 }
 
 base::TimeDelta ClipboardRecentContentIOS::Uptime() const {
   return base::SysInfo::Uptime();
 }