Use the password_manager encryptor to encrypt the sync credentials under

chrome/browser/sync/util/user_settings_posix.cc

 // Copyright (c) 2009 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 entry.
 //
 // Implement the storage of service tokens in memory.
 
 #include "chrome/browser/sync/util/user_settings.h"
 
+#include "chrome/browser/password_manager/encryptor.h"
+#include "chrome/browser/sync/util/query_helpers.h"
+
 namespace browser_sync {
 
-void UserSettings::ClearAllServiceTokens() {
-  service_tokens_.clear();
-}
-
 void UserSettings::SetAuthTokenForService(
     const std::string& email,
     const std::string& service_name,
     const std::string& long_lived_service_token) {
-  service_tokens_[service_name] = long_lived_service_token;
+  std::string encrypted_service_token;
+  if (!Encryptor::EncryptString(long_lived_service_token,
+                                &encrypted_service_token)) {
+    LOG(ERROR) << "Encrytion failed: " << long_lived_service_token;
+    return;
+  }
+  ScopedDBHandle dbhandle(this);
+  ExecOrDie(dbhandle.get(), "INSERT INTO cookies "
+            "(email, service_name, service_token) "
+            "values (?, ?, ?)", email, service_name, encrypted_service_token);
+}
+
+void UserSettings::ClearAllServiceTokens() {
+  ScopedDBHandle dbhandle(this);
+  ExecOrDie(dbhandle.get(), "DELETE FROM cookies");
+}
+
+bool UserSettings::GetLastUser(std::string* username) {
+  ScopedDBHandle dbhandle(this);
+  ScopedStatement query(PrepareQuery(dbhandle.get(),
+      "SELECT email FROM cookies"));
+  if (SQLITE_ROW == sqlite3_step(query.get())) {
+    GetColumn(query.get(), 0, username);
+    return true;
+  } else {
+    return false;
+  }
 }
 
 bool UserSettings::GetLastUserAndServiceToken(const std::string& service_name,
                                               std::string* username,
                                               std::string* service_token) {
-  ServiceTokenMap::const_iterator iter = service_tokens_.find(service_name);
+  ScopedDBHandle dbhandle(this);
+  ScopedStatement query(PrepareQuery(
+      dbhandle.get(),
+      "SELECT email, service_token FROM cookies WHERE service_name = ?",
+      service_name));
 
-  if (iter != service_tokens_.end()) {
-    *username = email_;
-    *service_token = iter->second;
+  if (SQLITE_ROW == sqlite3_step(query.get())) {
+    std::string encrypted_service_token;
+    GetColumn(query.get(), 1, &encrypted_service_token);
+    if (!Encryptor::DecryptString(encrypted_service_token, service_token)) {
+      LOG(ERROR) << "Decryption failed: " << encrypted_service_token;
+      return false;
+    }
+    GetColumn(query.get(), 0, username);
     return true;
   }
 
   return false;
 }
 
 }  // namespace browser_sync