Revert of Save and restore unified mode

Revert of Save and restore unified mode (patchset #5 id:140001 of https://codereview.chromium.org/1150913002/)

Reason for revert:
Revert due to memory leak.

Direct leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x61740b in operator new(unsigned long) (/tmp/run_tha_testilFjDM/out/Release/unit_tests+0x61740b)
    #1 0x40206a0 in chromeos::(anonymous namespace)::DisplayPreferencesTest::StoreDisplayBoolPropertyForPair(std::pair\u003Clong, long> const&, std::string const&, bool) chrome/browser/chromeos/display/display_preferences_unittest.cc:146:44
    #2 0x401e200 in chromeos::DisplayPreferencesTest_RestoreUnifiedMode_Test::TestBody() chrome/browser/chromeos/display/display_preferences_unittest.cc:925:3

Original issue's description:
> Save and restore unified mode
>
> BUG=489809
> TEST=DisplayPreferenceTest.SaveUnifiedMode/RestoreUnifiedMode
>
> Committed: https://crrev.com/b83c400b39840d0c18bd113559ea0040eb3c6b46
> Cr-Commit-Position: refs/heads/master@{#331076}

TBR=mukai@chromium.org,oshima@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=489809
Committed: https://crrev.com/de0c9e02748a95c5f93a236354e52fdacad53caa
Cr-Commit-Position: refs/heads/master@{#331087}

[battre, 2015-05-22 09:46:55]

Created Revert of Save and restore unified mode

[commit-bot: I haz the power, 2015-05-22 09:47:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149063004/1

[commit-bot: I haz the power, 2015-05-22 09:48:16]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-22 09:49:09]

Patchset 1 (id:??) landed as
https://crrev.com/de0c9e02748a95c5f93a236354e52fdacad53caa
Cr-Commit-Position: refs/heads/master@{#331087}