Fix occasional crash in remote commands code

components/policy/core/common/cloud/cloud_policy_core.cc

Index: components/policy/core/common/cloud/cloud_policy_core.cc
diff --git a/components/policy/core/common/cloud/cloud_policy_core.cc b/components/policy/core/common/cloud/cloud_policy_core.cc
index 302808e16d8f40562e266ef5556fdf7c9fa67cec..a2fd68e588f7e0ff9ee656b005a4988a0404338b 100644
--- a/components/policy/core/common/cloud/cloud_policy_core.cc
+++ b/components/policy/core/common/cloud/cloud_policy_core.cc
@@ -49,6 +49,7 @@ void CloudPolicyCore::Disconnect() {
     FOR_EACH_OBSERVER(Observer, observers_, OnCoreDisconnecting(this));
   refresh_delay_.reset();
   refresh_scheduler_.reset();
+  remote_commands_service_.reset();

[bartfab (slow), 2015/05/18 12:24:49]

If another Connect() call is made later, will StartRemoteCommandsService() run
and recreate the |remote_commands_service_|?

[binjin, 2015/05/18 12:28:56]

No. Unless another StartRemoteCommandsService call is made explicitly.

I don't see this as an issue, since the first Connect() call doesn't call
StartRemoteCommandsService() itself either.

[bartfab (slow), 2015/05/18 12:30:45]

Sure, it does not need to be automatic and tied to each other. What I want to
understand is whether in the flows we have in the code right now, Connect() and
StartRemoteCommandsService() are called alongside each other so that we do not
end up with a remote commands service in some cases and without one in others.

[binjin, 2015/05/18 12:37:12]

I see. I did a grep and the only place where StartRemoteCommandsService is
called is at device_cloud_policy_manager_chromeos.cc, following the Connect()
call.      

There are multiple places where Connect() is called, but for device remote
commands, it's also the only place. So I think we will have
RemoteCommandsService running in that case.

[bartfab (slow), 2015/05/19 09:31:08]

I checked: All the other Connect() calls deal with user policy and we do not
have per-user commands yet. So we have confirmation that yes,
StartRemoteCommandsService() will always be called together with Connect() for
the Core that handles device policy (and device-wide commands).

   service_.reset();
   client_.reset();
 }