Remove the tracing cache backend.

Remove the tracing cache backend.

While working on issue 410276, in particular in
https://codereview.chromium.org/542733002/ , I had to update the
tracing cache backend. Why? Does anyone use it?

Let's remove it instead.

R=pasko@chromium.org,clamy@chromium.org
BUG=None

Committed: https://crrev.com/b8af58ec40a0a122a5effa74958c00b2513bd660
Cr-Commit-Position: refs/heads/master@{#293505}

[gavinp, 2014-09-05 01:12:33]

Patchset #2 (id:20001) has been deleted

[gavinp, 2014-09-05 01:21:40]

Egor: PTAL, -500 lines is a productive week! Let's attribute -250 to each of us.

clamy: FYI.

[pasko, 2014-09-05 09:26:06]

LGTM

Thank you. I am somewhat upset that I did not manage to do it myself.

[gavinp, 2014-09-05 11:04:18]

The CQ bit was checked by gavinp@chromium.org

[commit-bot: I haz the power, 2014-09-05 11:04:50]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/gavinp@chromium.org/544923002/1

[commit-bot: I haz the power, 2014-09-05 12:15:37]

Committed patchset #1 (id:1) as aa4ad8dbd1abd884e50bd2c925b0d6c6cd77f20b

[commit-bot: I haz the power, 2014-09-10 03:39:00]

Patchset 1 (id:??) landed as
https://crrev.com/b8af58ec40a0a122a5effa74958c00b2513bd660
Cr-Commit-Position: refs/heads/master@{#293505}