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

components/components_tests.gyp

Index: components/components_tests.gyp
diff --git a/components/components_tests.gyp b/components/components_tests.gyp
index bfd1fd36571afb17c9472e697b7335dd5ec68d33..f3f37ef5832235083e4a669113a6312632ee3df5 100644
--- a/components/components_tests.gyp
+++ b/components/components_tests.gyp
@@ -453,6 +453,7 @@
       'open_from_clipboard/clipboard_recent_content_ios_unittest.mm',
     ],
     'os_crypt_unittest_sources': [
+      'os_crypt/os_crypt_util_linux_unittest.cc',
       'os_crypt/ie7_password_win_unittest.cc',
       'os_crypt/keychain_password_mac_unittest.mm',
       'os_crypt/os_crypt_unittest.cc',
@@ -1513,6 +1514,12 @@
             '../dbus/dbus.gyp:dbus',
             '../device/media_transfer_protocol/media_transfer_protocol.gyp:device_media_transfer_protocol',
           ],
+          'defines': [
+            'USE_LIBSECRET',
+          ],
+          'include_dirs': [
+            '../third_party/libsecret'
+          ],
         }],
         ['OS=="linux" and use_udev==0', {
           'dependencies!': [