Speculatively fix OSX crashes involving service removal

Speculatively fix OSX crashes involving service removal

Don't signal a service is removed unless we've signaled it was added.

BUG=365835
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=278542

[Vitaly Buka (NO REVIEWS), 2014-06-19 18:22:23]

lgtm

[commit-bot: I haz the power, 2014-06-19 18:27:59]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/noamsml@chromium.org/346873002/1

[commit-bot: I haz the power, 2014-06-19 22:52:45]

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/8...)

[commit-bot: I haz the power, 2014-06-19 23:02:37]

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

[commit-bot: I haz the power, 2014-06-19 23:02:38]

Try jobs failed on following builders:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/8...)

[Noam Samuel, 2014-06-19 23:09:07]

The CQ bit was checked by noamsml@chromium.org

[commit-bot: I haz the power, 2014-06-19 23:10:40]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/noamsml@chromium.org/346873002/1

[commit-bot: I haz the power, 2014-06-20 00:09:39]

Change committed as 278542