Wait for toggle_touch_event_logging to exit so we don't leave zombie processes

Wait for toggle_touch_event_logging to exit so we don't leave zombie processes

BUG=376806
TEST=bring up/dismiss the virtual keyboard a few times and then run ps aux to
make sure there is no defunct chrome process.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=273064

[kevers, 2014-05-26 22:58:40]

lgtm

[Yufeng Shen (Slow to review), 2014-05-26 22:59:08]

The CQ bit was checked by miletus@chromium.org

[commit-bot: I haz the power, 2014-05-26 22:59:30]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/miletus@chromium.org/297173003/1

[commit-bot: I haz the power, 2014-05-27 02:00:45]

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:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/7...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-05-27 02:23:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-27 02:23:33]

Try jobs failed on following builders:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/7...)

[Yufeng Shen (Slow to review), 2014-05-27 16:26:31]

The CQ bit was checked by miletus@chromium.org

[commit-bot: I haz the power, 2014-05-27 16:27:29]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/miletus@chromium.org/297173003/1

[commit-bot: I haz the power, 2014-05-27 16:51:30]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/7...)

[commit-bot: I haz the power, 2014-05-27 16:58:03]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-27 16:58:03]

Try jobs failed on following builders:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/7...)

[Yufeng Shen (Slow to review), 2014-05-27 21:49:10]

The CQ bit was checked by miletus@chromium.org

[commit-bot: I haz the power, 2014-05-27 21:49:57]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/miletus@chromium.org/297173003/1

[commit-bot: I haz the power, 2014-05-27 22:58:10]

Change committed as 273064