OSCrypt for POSIX uses libsecret to store a randomised encryption key.

chrome/browser/password_manager/native_backend_libsecret.h

 // Copyright (c) 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 CHROME_BROWSER_PASSWORD_MANAGER_NATIVE_BACKEND_LIBSECRET_H_
 #define CHROME_BROWSER_PASSWORD_MANAGER_NATIVE_BACKEND_LIBSECRET_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "base/time/time.h"
 #include "chrome/browser/password_manager/password_store_factory.h"
 #include "chrome/browser/password_manager/password_store_x.h"
 #include "chrome/browser/profiles/profile.h"
-#include "components/os_crypt/libsecret_util_posix.h"
+#include "components/os_crypt/libsecret_util_linux.h"
 
 namespace autofill {
 struct PasswordForm;
 }
 
 class NativeBackendLibsecret : public PasswordStoreX::NativeBackend {
  public:
   explicit NativeBackendLibsecret(LocalProfileId id);
 
   ~NativeBackendLibsecret() override;
@@ skipping 72 matching lines @@
       GList* found,
       const autofill::PasswordForm* lookup_form);
 
   // The app string, possibly based on the local profile id.
   std::string app_string_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeBackendLibsecret);
 };
 
 #endif  // CHROME_BROWSER_PASSWORD_MANAGER_NATIVE_BACKEND_LIBSECRET_H_