Add an identity component for unique/opaque url::Origins.

url/origin.h

 // 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.
 
 #ifndef URL_ORIGIN_H_
 #define URL_ORIGIN_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 32 matching lines @@
 // * Invalid and non-standard GURLs are parsed as unique origins. This includes
 //   non-hierarchical URLs like 'data:text/html,...' and 'javascript:alert(1)'.
 //
 // * GURLs with schemes of 'filesystem' or 'blob' parse the origin out of the
 //   internals of the URL. That is, 'filesystem:https://example.com/temporary/f'
 //   is parsed as ('https', 'example.com', 443).
 //
 // * Unique origins all serialize to the string "null"; this means that the
 //   serializations of two unique origins are identical to each other, though
 //   the origins themselves are not "the same". This means that origins'
 //   serializations must not be relied upon for security checks.

[Mike West, 2017/02/24 07:58:50]

Please update these comments as well.

 //
 // * GURLs with a 'file' scheme are tricky. They are parsed as ('file', '', 0),
 //   but their behavior may differ from embedder to embedder.
 //
 // * The host component of an IPv6 address includes brackets, just like the URL
 //   representation.
 //
 // Usage:
 //
 // * Origins are generally constructed from an already-canonicalized GURL:
@@ skipping 103 matching lines @@
          base::StringPiece host,
          uint16_t port,
          base::StringPiece suborigin,
          SchemeHostPort::ConstructPolicy policy);
   Origin(std::string scheme,
          std::string host,
          uint16_t port,
          std::string suborigin,
          SchemeHostPort::ConstructPolicy policy);
 
+  bool unique_;
+
   SchemeHostPort tuple_;
-  bool unique_;
   std::string suborigin_;
+
+  uint8_t unique_origin_id_[16];
 };
 
 URL_EXPORT std::ostream& operator<<(std::ostream& out, const Origin& origin);
 
 URL_EXPORT bool IsSameOriginWith(const GURL& a, const GURL& b);
 URL_EXPORT bool IsSamePhysicalOriginWith(const GURL& a, const GURL& b);
 
 }  // namespace url
 
 #endif  // URL_ORIGIN_H_