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..3345ca06450672d525699cf463f3e3cb59fa76c0 100644
--- a/components/components_tests.gyp
+++ b/components/components_tests.gyp
@@ -459,6 +459,7 @@
       'open_from_clipboard/clipboard_recent_content_ios_unittest.mm',
     ],
     'os_crypt_unittest_sources': [
+      'os_crypt/os_crypt_util_linux_unittest.cc',

[Lei Zhang, 2016/05/18 22:38:15]

Alphabetical order please. Ditto below.

[cfroussios, 2016/05/19 21:18:17]

Done.

       'os_crypt/ie7_password_win_unittest.cc',
       'os_crypt/keychain_password_mac_unittest.mm',
       'os_crypt/os_crypt_unittest.cc',
@@ -1500,6 +1501,7 @@
           'sources!': [
             'signin/core/browser/signin_status_metrics_provider_unittest.cc',
             'storage_monitor/storage_monitor_linux_unittest.cc',
+            'os_crypt/os_crypt_util_linux_unittest.cc',
           ],
           'dependencies': [
             '../chromeos/chromeos.gyp:chromeos_test_support',
@@ -1522,6 +1524,14 @@
             '../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',