Convert iOS to use X509CertificateBytes.

net/base/net_string_util_icu_alternatives_ios.mm

 // Copyright 2016 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 <CoreFoundation/CoreFoundation.h>
+
 #include "base/logging.h"
+#include "base/mac/scoped_cftyperef.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_piece.h"
+#include "base/strings/sys_string_conversions.h"
 #include "net/base/net_string_util.h"
 
 namespace net {
 
+namespace {
+
+bool CharsetToCFStringEncoding(const char* charset,
+                               CFStringEncoding* encoding) {
+  if (charset == kCharsetLatin1 || strcmp(charset, kCharsetLatin1) == 0) {
+    *encoding = kCFStringEncodingISOLatin1;
+    return true;
+  }
+  // TODO(mattm): handle other charsets? See
+  // https://developer.apple.com/reference/corefoundation/cfstringbuiltinencodings?language=objc
+  // for list of standard CFStringEncodings.
+
+  return false;
+}
+
+}  // namespace
+
 // This constant cannot be defined as const char[] because it is initialized
 // by base::kCodepageLatin1 (which is const char[]) in net_string_util_icu.cc.
 const char* const kCharsetLatin1 = "ISO-8859-1";
 
 bool ConvertToUtf8(const std::string& text,
                    const char* charset,
                    std::string* output) {
-  DCHECK(false) << "Not implemented yet.";
-  return false;
+  CFStringEncoding encoding;
+  if (!CharsetToCFStringEncoding(charset, &encoding))
+    return false;
+
+  base::ScopedCFTypeRef<CFStringRef> cfstring(CFStringCreateWithBytes(
+      kCFAllocatorDefault, reinterpret_cast<const UInt8*>(text.data()),
+      base::checked_cast<CFIndex>(text.length()), encoding,
+      false /* isExternalRepresentation */));
+  if (!cfstring)
+    return false;
+  *output = base::SysCFStringRefToUTF8(cfstring.get());
+  return true;
 }
 
 bool ConvertToUtf8AndNormalize(const std::string& text,
                                const char* charset,
                                std::string* output) {
   DCHECK(false) << "Not implemented yet.";
   return false;
 }
 
 bool ConvertToUTF16(const std::string& text,
                     const char* charset,
                     base::string16* output) {
   DCHECK(false) << "Not implemented yet.";
   return false;
 }
 
 bool ConvertToUTF16WithSubstitutions(const std::string& text,
                                      const char* charset,
                                      base::string16* output) {
   DCHECK(false) << "Not implemented yet.";
   return false;
 }
 
-}  // namespace net
+}  // namespace net