[TSAN] Fix data race with base::i18n text direction.

[TSAN] Fix data race with base::i18n text direction.

The global g_icu_text_direction could be read/written from
any thread that called base::i18n::IsRTL resulting in a data race.
Guard read/writes with a mutex.

BUG=695929
TEST=base_unittests

Review-Url: https://codereview.chromium.org/2716003002
Cr-Commit-Position: refs/heads/master@{#454108}
Committed: https://chromium.googlesource.com/chromium/src/+/d27e590ad6471e444e164597ee22a80c7801451d

[mbjorge, 2017-02-24 18:25:55]

mbjorge@chromium.org changed reviewers:
+ jshin@chromium.org

[jungshik at Google, 2017-03-01 22:42:27]

LGTM
Sorry for the delay.

[mbjorge, 2017-03-01 22:57:30]

The CQ bit was checked by mbjorge@chromium.org

[commit-bot: I haz the power, 2017-03-01 22:58:57]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-02 00:07:49]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1488409050778900, "parent_rev":
"fff4cd8691021ffe01c99480a33a14d06e3eae22", "commit_rev":
"d27e590ad6471e444e164597ee22a80c7801451d"}

[commit-bot: I haz the power, 2017-03-02 00:08:24]

Description was changed from

==========
[TSAN] Fix data race with base::i18n text direction.

The global g_icu_text_direction could be read/written from
any thread that called base::i18n::IsRTL resulting in a data race.
Guard read/writes with a mutex.

BUG=695929
TEST=base_unittests
==========

to

==========
[TSAN] Fix data race with base::i18n text direction.

The global g_icu_text_direction could be read/written from
any thread that called base::i18n::IsRTL resulting in a data race.
Guard read/writes with a mutex.

BUG=695929
TEST=base_unittests

Review-Url: https://codereview.chromium.org/2716003002
Cr-Commit-Position: refs/heads/master@{#454108}
Committed:
https://chromium.googlesource.com/chromium/src/+/d27e590ad6471e444e164597ee22...
==========

[commit-bot: I haz the power, 2017-03-02 00:08:26]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/d27e590ad6471e444e164597ee22...

[RE66, 2017-03-02 04:24:49]

On 2017/03/02 00:08:26, commit-bot: I haz the power wrote:
> Committed patchset #1 (id:1) as
>
https://chromium.googlesource.com/chromium/src/+/d27e590ad6471e444e164597ee22...

this fix has huge bad performance impact.
IsRTL is called millions of times adding millions of heavy lock
while initialized one 
Chrome has a mechanism to verify that global vars are initialized before used m
use it, ask colleagues at google

Even if no such mechanism exists the performance impact is so terrible that the
low probability 
of reading before writing is better solution

[mbjorge, 2017-03-02 17:35:51]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2722413004/ by mbjorge@chromium.org.

The reason for reverting is: IsRTL is called a lot and this caused serious
performance impact..

[mbjorge, 2017-03-03 18:56:10]

On 2017/03/02 at 17:35:51, mbjorge wrote:
> A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2722413004/ by mbjorge@chromium.org.
> 
> The reason for reverting is: IsRTL is called a lot and this caused serious
performance impact..

Just curious, RonEfrati@ do you have specific numbers to quantify the
performance impact?