external metrics: change event file location

external metrics: change event file location

This file used to be in /tmp, but then the security folks
decided that /tmp was too dangerous and it got moved to
/var/log, but that's the wrong place for it.
The corresponding Chrome OS change has just been pushed at
https://chromium-review.googlesource.com/#/c/200091/

BUG=chromium:373833
TEST=none

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=271289

[Luigi Semenzato, 2014-05-16 17:46:44]

Hi Ricardo,

sorry to bother you with this but would you be so kind to review AND PUSH this
(since I don't have commit privileges).  I made the change on the Chrome OS side
but Dan is OOO for a long week-end.  Thank you!

[rvargas (doing something else), 2014-05-16 19:09:31]

Looks good buy my opinion is not worth much. Unfortunately I'm not an owner of
chrome/browser so someone else still has to review it. I semi-randomly picked
+davemoore

[Daniel Erat, 2014-05-17 14:15:22]

lgtm

[commit-bot: I haz the power, 2014-05-17 14:16:41]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/semenzato@chromium.org/292433009/1

[commit-bot: I haz the power, 2014-05-17 18:19:48]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-05-18 14:08:47]

Change committed as 271289