Revert of [tracing] Display the locked size of discardable memory segment.

Revert of [tracing] Display the locked size of discardable memory segment. (patchset #8 id:200001 of https://codereview.chromium.org/1374213002/ )

Reason for revert:
Speculative revert for the bug: www.crbug.com/541029

Original issue's description:
> [tracing] Display the locked size of discardable memory segment.
>
> The locked size of the discardable memory segments is now displayed on
> tracing. The browser side can only tell if the whole segment is locked
> or not, if the segment is shared with a child. The child side can also
> tell how much memory in the segment is locked.
>
> BUG=529943
>
> Committed: https://crrev.com/a29f3c7b772a058c69b91d393740b85d7d23526b
> Cr-Commit-Position: refs/heads/master@{#352004}

TBR=reveman@chromium.org,avi@chromium.org,thestig@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=529943
Committed: https://crrev.com/759242daa7de8683f62885673b5dfba75679727b
Cr-Commit-Position: refs/heads/master@{#353260}

[ssid, 2015-10-09 10:34:48]

Created Revert of [tracing] Display the locked size of discardable memory
segment.

[ssid, 2015-10-09 10:35:08]

The CQ bit was checked by ssid@chromium.org

[commit-bot: I haz the power, 2015-10-09 10:36:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1386333003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1386333003/1

[commit-bot: I haz the power, 2015-10-09 10:37:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-09 10:38:40]

Patchset 1 (id:??) landed as
https://crrev.com/759242daa7de8683f62885673b5dfba75679727b
Cr-Commit-Position: refs/heads/master@{#353260}

[ssid, 2015-10-13 14:57:10]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1407483003/ by ssid@chromium.org.

The reason for reverting is: Reland after the fix..