Exempt Save-Data header from CORS preflight request check

third_party/WebKit/Source/core/fetch/FetchUtils.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 "core/fetch/FetchUtils.h"
 
 #include "platform/network/HTTPHeaderMap.h"
 #include "platform/network/HTTPParsers.h"
 #include "wtf/HashSet.h"
 #include "wtf/Threading.h"
@@ skipping 72 matching lines @@
 }
 
 bool FetchUtils::isSimpleHeader(const AtomicString& name, const AtomicString& value)
 {
     // http://fetch.spec.whatwg.org/#simple-header
     // "A simple header is a header whose name is either one of `Accept`,
     // `Accept-Language`, and `Content-Language`, or whose name is
     // `Content-Type` and value, once parsed, is one of
     // `application/x-www-form-urlencoded`, `multipart/form-data`, and
     // `text/plain`."
+    // Treat 'Save-Data' as a simple header, since it is added by Chrome when
+    // Data Saver feature is enabled.
 
     if (equalIgnoringCase(name, "accept")
         || equalIgnoringCase(name, "accept-language")
-        || equalIgnoringCase(name, "content-language"))
+        || equalIgnoringCase(name, "content-language")
+        || equalIgnoringCase(name, "save-data"))
         return true;
 
     if (equalIgnoringCase(name, "content-type")) {
         AtomicString mimeType = extractMIMETypeFromMediaType(value);
         return equalIgnoringCase(mimeType, "application/x-www-form-urlencoded")
             || equalIgnoringCase(mimeType, "multipart/form-data")
             || equalIgnoringCase(mimeType, "text/plain");
     }
 
     return false;
@@ skipping 89 matching lines @@
 String FetchUtils::normalizeHeaderValue(const String& value)
 {
     // https://fetch.spec.whatwg.org/#concept-header-value-normalize
     // Strip leading and trailing whitespace from header value.
     // HTTP whitespace bytes are 0x09, 0x0A, 0x0D, and 0x20.
 
     return value.stripWhiteSpace(isHTTPWhitespace);
 }
 
 } // namespace blink