net: add IsMethodIdempotent() to HttpUtil

net/http/http_util.h

 // Copyright (c) 2012 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.
 
 #ifndef NET_HTTP_HTTP_UTIL_H_
 #define NET_HTTP_HTTP_UTIL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 57 matching lines @@
 
   // Parses a Retry-After header that is either an absolute date/time or a
   // number of seconds in the future. Interprets absolute times as relative to
   // |now|. If |retry_after_string| is successfully parsed and indicates a time
   // that is not in the past, fills in |*retry_after| and returns true;
   // otherwise, returns false.
   static bool ParseRetryAfterHeader(const std::string& retry_after_string,
                                     base::Time now,
                                     base::TimeDelta* retry_after);
 
-  // True if the request method is "safe" (per section 4.2.1 of RFC 7231).
+  // Returns true if the request method is "safe" (per section 4.2.1 of
+  // RFC 7231).
   static bool IsMethodSafe(const std::string& method);
 
+  // Returns true if the request method is idempotent (per section 4.2.2 of
+  // RFC 7231).
+  static bool IsMethodIdempotent(const std::string& method);
+
   // Returns true if it is safe to allow users and scripts to specify the header
   // named |name|.
   static bool IsSafeHeader(const std::string& name);
 
   // Returns true if |name| is a valid HTTP header name.
   static bool IsValidHeaderName(const base::StringPiece& name);
 
   // Returns false if |value| contains NUL or CRLF. This method does not perform
   // a fully RFC-2616-compliant header value validation.
   static bool IsValidHeaderValue(const base::StringPiece& value);
@@ skipping 353 matching lines @@
     // True if quotes values are required to be properly quoted; false if
     // mismatched quotes and other problems with quoted values should be more
     // or less gracefully treated as valid.
     bool strict_quotes_;
   };
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_UTIL_H_