Use LowerASCII() for MIME type lowering

third_party/WebKit/Source/modules/fetch/FetchHeaderList.cpp

 // 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.
 
 #include "modules/fetch/FetchHeaderList.h"
 
 #include <algorithm>
 #include <utility>
 #include "platform/loader/fetch/FetchUtils.h"
 #include "platform/network/HTTPParsers.h"
@@ skipping 51 matching lines @@
 
 String FetchHeaderList::ExtractMIMEType() const {
   // To extract a MIME type from a header list (headers), run these steps:
   // 1. Let MIMEType be the result of parsing `Content-Type` in headers.
   String mime_type;
   if (!Get("Content-Type", mime_type)) {
     // 2. If MIMEType is null or failure, return the empty byte sequence.
     return String();
   }
   // 3. Return MIMEType, byte lowercased.
-  return mime_type.DeprecatedLower();
+  return mime_type.LowerASCII();
 }
 
 size_t FetchHeaderList::size() const {
   return header_list_.size();
 }
 
 void FetchHeaderList::Remove(const String& name) {
   // https://fetch.spec.whatwg.org/#concept-header-list-delete
   // "To delete a name (name) from a header list (list), remove all headers
   // whose name is a byte-case-insensitive match for name from list."
@@ skipping 82 matching lines @@
   return IsValidHTTPToken(name);
 }
 
 bool FetchHeaderList::IsValidHeaderValue(const String& value) {
   // "A value is a byte sequence that matches the field-value token production
   // and contains no 0x0A or 0x0D bytes."
   return IsValidHTTPHeaderValue(value);
 }
 
 }  // namespace blink