[Ozone-Dri] Make GbmWrapper destructor private

[Ozone-Dri] Make GbmWrapper destructor private

It fixes the following clang format:

In file included from ../../ui/ozone/platform/dri/gbm_surface.cc:14:
../../ui/ozone/platform/dri/gbm_wrapper.h:18:3: error: [chromium-style] Classes that are ref-counted should have destructors that are declared protected or private.
  ~GbmWrapper() override;
  ^
../../ui/ozone/platform/dri/gbm_wrapper.h:14:20: note: [chromium-style] 'GbmWrapper' inherits from 'ui::DriWrapper' here
class GbmWrapper : public DriWrapper {
                   ^
../../ui/ozone/platform/dri/dri_wrapper.h:41:33: note: [chromium-style] 'DriWrapper' inherits from 'base::RefCountedThreadSafe<DriWrapper>' here
class OZONE_EXPORT DriWrapper : public base::RefCountedThreadSafe<DriWrapper> {
                                ^
BUG=none

Committed: https://crrev.com/34108a53235e8c61d625ad80db7941edf1684084
Cr-Commit-Position: refs/heads/master@{#317300}

[vignatti (out of this project), 2015-02-19 22:29:44]

tiago.vignatti@intel.com changed reviewers:
+ dnicoara@chromium.org

[vignatti (out of this project), 2015-02-19 22:30:02]

dnicoara@ PTAL.

[spang, 2015-02-19 23:09:42]

spang@chromium.org changed reviewers:
+ spang@chromium.org

[spang, 2015-02-19 23:09:43]

lgtm

[vignatti (out of this project), 2015-02-20 12:14:42]

The CQ bit was checked by tiago.vignatti@intel.com

[commit-bot: I haz the power, 2015-02-20 12:15:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/940223002/1

[commit-bot: I haz the power, 2015-02-20 12:35:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-20 12:36:09]

Patchset 1 (id:??) landed as
https://crrev.com/34108a53235e8c61d625ad80db7941edf1684084
Cr-Commit-Position: refs/heads/master@{#317300}