printing: Use MD5DigestToBase16() to get a human-readable hexadecimal string.

printing: Use MD5DigestToBase16() to get a human-readable hexadecimal string.

It seems better to use a specific MD5 API for this kind of thing.

The result should be the same with the difference that the alpha chars
used in MD5DigestToBase16() are lowercase.

BUG=None
TEST=components_browsertests --gtest_filter=PrintWebViewHelperTest.PrintLayoutTest
R=vitalybuka@chromium.org

Committed: https://crrev.com/0a9c25c5a7f8cec0699401bb0328dd6df9d9cb13
Cr-Commit-Position: refs/heads/master@{#324186}

[tfarina, 2015-04-06 23:56:05]

Is this OK? ptal

[Vitaly Buka (NO REVIEWS), 2015-04-07 00:14:17]

lgtm

[tfarina, 2015-04-08 02:21:49]

The CQ bit was checked by tfarina@chromium.org

[commit-bot: I haz the power, 2015-04-08 02:22:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1068593002/1

[commit-bot: I haz the power, 2015-04-08 04:44:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-08 04:45:22]

Patchset 1 (id:??) landed as
https://crrev.com/0a9c25c5a7f8cec0699401bb0328dd6df9d9cb13
Cr-Commit-Position: refs/heads/master@{#324186}