Overload << operator to allow logging of AccountIds.

components/signin/core/account_id/account_id.cc

 // 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.
 
 #include "components/signin/core/account_id/account_id.h"
 
 #include <functional>
 #include <memory>
 
 #include "base/json/json_reader.h"
@@ skipping 301 matching lines @@
 
     case AccountType::UNKNOWN:
       if (!found_user_email)
         return false;
       *account_id = FromUserEmail(user_email);
       return true;
   }
   return false;
 }
 
+std::ostream& operator<<(std::ostream& stream, const AccountId& account_id) {
+  stream << "{id: " << account_id.id_ << ", email: " << account_id.user_email_
+         << ", type: "
+         << static_cast<
+                std::underlying_type<decltype(account_id.account_type_)>::type>(
+                account_id.account_type_)
+         << "}";
+  return stream;
+}
+
 const AccountId& EmptyAccountId() {
   return AccountId::EmptyAccountId::GetInstance()->user_id;
 }
 
 namespace BASE_HASH_NAMESPACE {
 
 std::size_t hash<AccountId>::operator()(const AccountId& user_id) const {
   return hash<std::string>()(user_id.GetUserEmail());
 }
 
 }  // namespace BASE_HASH_NAMESPACE