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

Revert of Revert of MSan: check data is initialized when serializing with base::Pickle. (patchset #1 id:1 of https://codereview.chromium.org/985893002/)

Reason for revert:
The bugs that caused the revert have been fixed - Unreverting.

Original issue's description:
> Revert of MSan: check data is initialized when serializing with base::Pickle. (patchset #1 id:1 of https://codereview.chromium.org/988693004/)
>
> Reason for revert:
> Found errors w.r.t. IPC messages. Reverting for now while people fix the errors.
>
> Original issue's description:
> > 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}
>
> TBR=thakis@chromium.org,earthdok@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=463906
>
> Committed: https://crrev.com/d74906086c38b72bed2017a772c67f3c3fde2709
> Cr-Commit-Position: refs/heads/master@{#319510}

TBR=thakis@chromium.org,earthdok@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=463906
Committed: https://crrev.com/1a42b4077dd8b49ef92c5f9a517eeeb9bfc3be88
Cr-Commit-Position: refs/heads/master@{#320808}

[Lei Zhang, 2015-03-16 22:35:43]

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

[commit-bot: I haz the power, 2015-03-16 22:36:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1008393004/1

[commit-bot: I haz the power, 2015-03-16 22:37:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-16 22:37:35]

Patchset 1 (id:??) landed as
https://crrev.com/1a42b4077dd8b49ef92c5f9a517eeeb9bfc3be88
Cr-Commit-Position: refs/heads/master@{#320808}