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

components/os_crypt/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/ui.gni")
 
 source_set("os_crypt") {
   sources = [
     "ie7_password_win.cc",
     "ie7_password_win.h",
@@ skipping 26 matching lines @@
       "os_crypt_mac.mm",
     ]
     set_sources_assignment_filter(sources_assignment_filter)
   }
 
   if (is_win) {
     libs = [ "crypt32.lib" ]
   }
 
   if (is_desktop_linux && use_glib) {
+    sources -= [ "os_crypt_posix.cc" ]
     sources += [
-      "libsecret_util_posix.cc",
-      "libsecret_util_posix.h",
+      "key_storage_libsecret.cc",
+      "key_storage_libsecret.h",
+      "key_storage_linux.cc",
+      "key_storage_linux.h",
+      "libsecret_util_linux.cc",
+      "libsecret_util_linux.h",
+      "os_crypt_linux.cc",
     ]
     configs += [ "//build/config/linux:glib" ]
     deps += [ "//third_party/libsecret" ]
     defines = [ "USE_LIBSECRET" ]
   }
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "ie7_password_win_unittest.cc",
     "keychain_password_mac_unittest.mm",
     "os_crypt_unittest.cc",
   ]
   deps = [
     ":os_crypt",
     "//base",
     "//crypto",
     "//testing/gtest",
   ]
+
+  if (is_desktop_linux) {
+    sources += [
+      "os_crypt_mocker_linux.cc",
+      "os_crypt_mocker_linux.h",
+      "os_crypt_util_linux_unittest.cc",
+    ]
+    deps += [ "//third_party/libsecret" ]
+    defines = [ "USE_LIBSECRET" ]
+  }
 }