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 eb121d14b71f564a6865b4454e65b5579e99a418..6b9fc8086a66f0e49b272825a0eda68810149fc0 100644
--- a/components/components_tests.gyp
+++ b/components/components_tests.gyp
@@ -461,7 +461,10 @@
     'os_crypt_unittest_sources': [
       'os_crypt/ie7_password_win_unittest.cc',
       'os_crypt/keychain_password_mac_unittest.mm',
+      'os_crypt/key_storage_mock.cc',

[Lei Zhang, 2016/05/19 22:45:38]

In ASCII order, '_' comes be 'c'.

[cfroussios, 2016/05/20 16:44:52]

Done.

+      'os_crypt/key_storage_mock.h',
       'os_crypt/os_crypt_unittest.cc',
+      'os_crypt/os_crypt_util_linux_unittest.cc',
     ],
     'ownership_unittest_sources': [
       'ownership/owner_key_util_impl_unittest.cc',
@@ -1498,6 +1501,7 @@
             '<@(user_manager_unittest_sources)',
           ],
           'sources!': [
+            'os_crypt/os_crypt_util_linux_unittest.cc',
             'signin/core/browser/signin_status_metrics_provider_unittest.cc',
             'storage_monitor/storage_monitor_linux_unittest.cc',
           ],
@@ -1522,6 +1526,14 @@
             '../device/media_transfer_protocol/media_transfer_protocol.gyp:device_media_transfer_protocol',
           ],
         }],
+        ['OS=="linux" and chromeos!=1', {
+          'defines': [
+            'USE_LIBSECRET',
+          ],
+          'include_dirs': [
+            '../third_party/libsecret'
+          ],
+        }],
         ['OS=="linux" and use_udev==0', {
           'dependencies!': [
             'components.gyp:storage_monitor',