Overload << operator to allow logging of AccountIds.

components/signin/core/account_id/account_id.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 COMPONENTS_SIGNIN_CORE_ACCOUNT_ID_ACCOUNT_ID_H_
 #define COMPONENTS_SIGNIN_CORE_ACCOUNT_ID_ACCOUNT_ID_H_
 
 #include <stddef.h>
 
+#include <ostream>
 #include <string>
+
 #include "base/containers/hash_tables.h"
 
 enum class AccountType { UNKNOWN, GOOGLE, ACTIVE_DIRECTORY };
 
 // Type that contains enough information to identify user.
 //
 // TODO(alemate): we are in the process of moving away from std::string as a
 // type for storing user identifier to AccountId. At this time GaiaId is mostly
 // empty, so this type is used as a replacement for e-mail string.
 // But in near future AccountId will become full feature user identifier.
@@ skipping 69 matching lines @@
 
   // These are (for now) unstable and cannot be used to store serialized data to
   // persistent storage. Only in-memory storage is safe.
   // Serialize() returns JSON dictionary,
   // Deserialize() restores AccountId after serialization.
   std::string Serialize() const;
   static bool Deserialize(const std::string& serialized,
                           AccountId* out_account_id);
 
  private:
+  friend std::ostream& operator<<(std::ostream&, const AccountId&);
+
   AccountId(const std::string& id,
             const std::string& user_email,
             const AccountType& account_type);
 
   std::string id_;
   std::string user_email_;
   AccountType account_type_ = AccountType::UNKNOWN;
 };
 
+// Overload << operator to allow logging of AccountIds.
+std::ostream& operator<<(std::ostream& stream, const AccountId& account_id);
+
 // Returns a reference to a singleton.
 const AccountId& EmptyAccountId();
 
 namespace BASE_HASH_NAMESPACE {
 
 // Implement hashing of AccountId, so it can be used as a key in STL containers.
 template <>
 struct hash<AccountId> {
   std::size_t operator()(const AccountId& user_id) const;
 };
 
 }  // namespace BASE_HASH_NAMESPACE
 
 #endif  // COMPONENTS_SIGNIN_CORE_ACCOUNT_ID_ACCOUNT_ID_H_