Avoid creating new TestingPrefServiceSyncable

Avoid creating new TestingPrefServiceSyncable

Allow the unittest to use Profile::GetPref() instead of 
creating its own Pref.

This also helps to solve the unit test crash in 
https://codereview.chromium.org/11968032/.
Context: With https://codereview.chromium.org/11968032/, 
GTKThemeService will be started at Profile creation which 
creates Profile's Pref. Later the new 
TestingPrefServiceSyncable that is created in 
ProtocolHandlerRegistryTest::SetUp overwrites Profile's Pref 
and leads to a crash in GTKThemeService's d'tor due to 
invalid pointer.

TBR=ben@chromium.org 
BUG=none
TEST=ProtocolHandlerRegistryTest.*

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=181642

[Joe Thomas, 2013-02-06 01:21:52]

joi@

Could you please review this patch? It is mentioned as TODO in your name.

Thanks,

[Jói, 2013-02-06 12:29:14]

LGTM

[commit-bot: I haz the power, 2013-02-06 20:25:09]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/MHX348@motorola.com/12211026/1

[commit-bot: I haz the power, 2013-02-06 20:25:11]

Presubmit check for 12211026-1 failed and returned exit status 1.


Running presubmit commit checks ...

** Presubmit ERRORS **
Missing LGTM from an OWNER for files in these directories:
    chrome

[Joe Thomas, 2013-02-06 20:26:40]

+ Ben for OWNERS

[Joe Thomas, 2013-02-10 03:20:01]

TBR=ben

[commit-bot: I haz the power, 2013-02-10 03:20:28]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/MHX348@motorola.com/12211026/1

[commit-bot: I haz the power, 2013-02-10 05:25:23]

Change committed as 181642