Add null check for entries of volume items.

Add null check for entries of volume items.

VolumeItem.entry can be null in FSP volume, so this CL add null check before using them.
Also, make some annotation strict to detect missing null check in static analysis.

BUG=427819
TEST=Force VolumeItem.entry to be null manually and confirm that no error rises.

Committed: https://crrev.com/8f814cf5c21d6476349efda2f1c09489486a16eb
Cr-Commit-Position: refs/heads/master@{#302277}

[fukino, 2014-10-31 14:57:43]

fukino@chromium.org changed reviewers:
+ mtomasz@chromium.org

[fukino, 2014-10-31 14:57:43]

Tomasz, could you take a look? Thanks!

[mtomasz, 2014-10-31 15:17:30]

lgtm

[fukino, 2014-10-31 15:20:10]

On 2014/10/31 15:17:30, mtomasz wrote:
> lgtm

Thanks!

[fukino, 2014-10-31 15:20:11]

On 2014/10/31 15:17:30, mtomasz wrote:
> lgtm

Thanks!

[fukino, 2014-10-31 15:20:13]

The CQ bit was checked by fukino@chromium.org

[commit-bot: I haz the power, 2014-10-31 15:20:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/690283002/1

[commit-bot: I haz the power, 2014-10-31 16:12:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-31 16:13:01]

Patchset 1 (id:??) landed as
https://crrev.com/8f814cf5c21d6476349efda2f1c09489486a16eb
Cr-Commit-Position: refs/heads/master@{#302277}