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

components/os_crypt/os_crypt.h

Index: components/os_crypt/os_crypt.h
diff --git a/components/os_crypt/os_crypt.h b/components/os_crypt/os_crypt.h
index ecffa4e5ed4c8c81b4acde3b8169b156eb305f51..8024392bcd02013b1873c09d5bd196a2e653ce85 100644
--- a/components/os_crypt/os_crypt.h
+++ b/components/os_crypt/os_crypt.h
@@ -10,6 +10,10 @@
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "build/build_config.h"
+#if defined(USE_LIBSECRET)

[Lei Zhang, 2016/05/18 22:38:16]

Add a blank line separator

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

Done.

+#include "components/os_crypt/key_storage_linux.h"
+#include "components/os_crypt/key_storage_mock.h"
+#endif
 
 // The OSCrypt class gives access to simple encryption and decryption of
 // strings. Note that on Mac, access to the system Keychain is required and
@@ -43,6 +47,13 @@ class OSCrypt {
   static void UseMockKeychain(bool use_mock);
 #endif
 
+#if defined(USE_LIBSECRET)
+  // For unit testing purposes, use a mocked |KeyStorage| service.

[Lei Zhang, 2016/05/18 22:38:16]

Refer to variables as |var_name|, not classes.

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

Acknowledged.

+  // A reference is to the |KeyStorageMock| is returned, so that the test can
+  // manipulate the service.
+  static KeyStorageMock* UseMockKeyStorage(bool use_mock);

[Lei Zhang, 2016/05/18 22:38:16]

This sounds confusing. What does UseMock...(use_mock = false) mean?

UseMockKeychain() above is slightly better but still a bit vague. That and
nobody ever calls UseMockKeychain(false).

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

I changed it so that a pointer is no longer returned. I assume that was what
made it worse than UseMockKeychain()?

(use_mock = false) means to stop mocking and restore behaviour to whatever is
intended for real use. I think such a cleanup is necessary, since the
configuration is static and doesn't go away when a test is destroyed. With that
argument, UseMockKeychain(false) should also be used, but this CL is focused on
Linux stuff

+#endif
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(OSCrypt);
 };