libchromeos: Fix security review comments in TlsStream class

Fixed some comments/issues raised by Darren related to implementation
of TlsStream.

BUG=None
TEST=`FEATURES=test emerge-link libchromeos`

Change-Id: I088060d85ba32a93b6eb5762e9ce6b2686f7660c
Reviewed-on: https://chromium-review.googlesource.com/270340
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Darren Krahn <dkrahn@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
2 files changed