SecureBlob: Improve unit tests.

When SecureBlob stops inheriting from Blob we'll want to make sure that
functionality continues to work.

BUG=chromium:728047
TEST=New unit tests pass.

Change-Id: I23bbbc37287046ad48ad3b234d752fba934d8d9e
Reviewed-on: https://chromium-review.googlesource.com/1110150
Commit-Ready: Jorge Lucangeli Obes <jorgelo@chromium.org>
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
1 file changed