HRTFDatabaseLoader needs to acquire a lock when accessing m_hrtfDatabase

HRTFDatabaseLoader needs to acquire a lock when accessing m_hrtfDatabase

Currently HRTFDatabaseLoader::m_threadLock is acquired when accessing
m_databaseLoaderThread, but the lock is not needed because m_databaseLoaderThread
is not accessed by multiple threads.

What we need to protect is not m_databaseLoaderThread but m_hrtfDatabase,
which is accessed by multiple threads. This CL makes the fix.

BUG=415305
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184166

[haraken, 2014-10-22 05:19:17]

haraken@chromium.org changed reviewers:
+ oilpan-reviews@chromium.org, rtoy@chromium.org, tkent@chromium.org

[haraken, 2014-10-22 05:19:17]

Not directly related to the bug, this is a potential fix for threading races.

PTAL.

[tkent, 2014-10-22 05:44:05]

lgtm

[haraken, 2014-10-22 05:55:58]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2014-10-22 05:56:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/666213003/20001

[commit-bot: I haz the power, 2014-10-22 06:05:57]

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

[commit-bot: I haz the power, 2014-10-22 06:05:58]

Try jobs failed on following builders:
  android_chromium_gn_compile_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/android_chromium_gn_comp...)
  mac_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/28053)

[haraken, 2014-10-22 07:41:25]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2014-10-22 07:42:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/666213003/40001

[commit-bot: I haz the power, 2014-10-22 08:16:34]

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

[commit-bot: I haz the power, 2014-10-22 08:16:34]

Try jobs failed on following builders:
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)

[haraken, 2014-10-22 10:43:14]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2014-10-22 10:43:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/666213003/40001

[commit-bot: I haz the power, 2014-10-22 11:13:38]

Committed patchset #3 (id:40001) as 184166