Don't reset speech_recognition_manager_ in BrowserMainLoop::ShutdownThreadsAndCleanUp()

Don't reset speech_recognition_manager_ in BrowserMainLoop::ShutdownThreadsAndCleanUp()

Instead, let it be reset during the destruction of BrowserMainLoop, which
happens after the IO thread has been shutdown.

This prevents a race condition between ShutdownThreadsAndCleanUp() and the
destructor of InputTagSpeechDispatcherHost. The latter runs on the IO thread,
and could sometimes end up trying to use the SpeechRecognitionManager
at the same time as it was being destructed.

Tested by running WorkerTest.QueuedSharedWorkerShutdown a couple of hundred
times under ASan, as well as running existing speech tests.

BUG=none


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=149394

[hans, 2012-07-30 12:31:38]

satish: can you take a look?
sky: presubmit suggested you as OWNERS reviewer
jam: fyi

[hans, 2012-07-30 12:32:19]

-simonjam
+satish

[Satish, 2012-07-30 14:48:52]

lgtm

[jam, 2012-07-30 15:21:43]

lgtm

[hans, 2012-07-31 10:28:53]

sky: ping?

[sky, 2012-07-31 19:03:36]

LGTM.
John's LGTM was actually enough, you don't need the both of us.

[commit-bot: I haz the power, 2012-08-01 08:32:53]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/hans@chromium.org/10836007/1

[commit-bot: I haz the power, 2012-08-01 09:56:39]

Change committed as 149394