MSan: check data is initialized when serializing with base::Pickle.

MSan: check data is initialized when serializing with base::Pickle.

Serialization implies that the data is going to leave the process one way or
another, and it's never a good idea to leak uninitialized bytes. In most cases
MSan would catch this later on (e.g. on a write()). There are exceptions to
that, however, such as writing to shared memory. It doesn't hurt to have an
extra check here.

BUG=463906
R=thakis@chromium.org

Committed: https://crrev.com/2c705b038413d30d7aae5ff5d09882575e93c898
Cr-Commit-Position: refs/heads/master@{#319459}

[Nico, 2015-03-06 15:43:06]

lgtm

[earthdok, 2015-03-06 15:43:34]

The CQ bit was checked by earthdok@chromium.org

[commit-bot: I haz the power, 2015-03-06 15:43:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/988693004/1

[commit-bot: I haz the power, 2015-03-06 17:10:08]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-06 17:10:50]

Patchset 1 (id:??) landed as
https://crrev.com/2c705b038413d30d7aae5ff5d09882575e93c898
Cr-Commit-Position: refs/heads/master@{#319459}

[Lei Zhang, 2015-03-06 21:32:05]

thestig@chromium.org changed reviewers:
+ thestig@chromium.org

[Lei Zhang, 2015-03-06 21:32:06]

This is failing. I'll file bugs for the failures and revert this for now.
http://build.chromium.org/p/chromium.memory.fyi/builders/Linux%20MSan%20Tests...

[Lei Zhang, 2015-03-06 21:34:01]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/985893002/ by thestig@chromium.org.

The reason for reverting is: Found errors w.r.t. IPC messages. Reverting for now
while people fix the errors..