[battor agent] Make BattOr agent block until the BattOrAgent is created

[battor agent] Make BattOr agent block until the BattOrAgent is created

This fixes a crash that would be triggered when a command was sent to
the agent very quickly after it started. In this case, battor_agent_bin
would try to use the BattOrAgent before it was initialized, resulting
in a segfault.

BUG=620010
Committed: https://crrev.com/52328d3bf192548208dd14181f76dc63ba2b7512
Cr-Commit-Position: refs/heads/master@{#399906}

[charliea (OOO until 10-5), 2016-06-15 14:20:09]

Patchset #1 (id:1) has been deleted

[charliea (OOO until 10-5), 2016-06-15 14:20:48]

charliea@chromium.org changed reviewers:
+ aschulman@chromium.org

[aschulman, 2016-06-15 14:51:03]

LGTM, w/nit

https://codereview.chromium.org/2062393002/diff/20001/tools/battor_agent/batt...
File tools/battor_agent/battor_agent_bin.cc (right):

https://codereview.chromium.org/2062393002/diff/20001/tools/battor_agent/batt...
tools/battor_agent/battor_agent_bin.cc:145:
base::WaitableEvent::InitialState::NOT_SIGNALED);
I'd like to see a comment explaining why this particular waitable event is
needed since this was needed to fix a particularly nasty bug that wasn't obvious
when you first wrote the code for this thread.

[charliea (OOO until 10-5), 2016-06-15 15:09:17]

The CQ bit was checked by charliea@chromium.org

[charliea (OOO until 10-5), 2016-06-15 15:09:17]

The patchset sent to the CQ was uploaded after l-g-t-m from
aschulman@chromium.org
Link to the patchset: https://codereview.chromium.org/2062393002/#ps40001
(title: "Add comment about why sync is necessary")

[commit-bot: I haz the power, 2016-06-15 15:09:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2062393002/40001

[commit-bot: I haz the power, 2016-06-15 15:55:49]

Committed patchset #2 (id:40001)

[commit-bot: I haz the power, 2016-06-15 15:55:51]

CQ bit was unchecked

[commit-bot: I haz the power, 2016-06-15 15:56:58]

Description was changed from

==========
[battor agent] Make BattOr agent block until the BattOrAgent is created

This fixes a crash that would be triggered when a command was sent to
the agent very quickly after it started. In this case, battor_agent_bin
would try to use the BattOrAgent before it was initialized, resulting
in a segfault.

BUG=620010
==========

to

==========
[battor agent] Make BattOr agent block until the BattOrAgent is created

This fixes a crash that would be triggered when a command was sent to
the agent very quickly after it started. In this case, battor_agent_bin
would try to use the BattOrAgent before it was initialized, resulting
in a segfault.

BUG=620010

Committed: https://crrev.com/52328d3bf192548208dd14181f76dc63ba2b7512
Cr-Commit-Position: refs/heads/master@{#399906}
==========

[commit-bot: I haz the power, 2016-06-15 15:56:59]

Patchset 2 (id:??) landed as
https://crrev.com/52328d3bf192548208dd14181f76dc63ba2b7512
Cr-Commit-Position: refs/heads/master@{#399906}