[Ozone-Dri] Make GbmDevice destructor private

[Ozone-Dri] Make GbmDevice destructor private

It fixes the following clang format message:

In file included from ../../ui/ozone/platform/dri/gbm_buffer.cc:14:
../../ui/ozone/platform/dri/gbm_device.h:18:3: error: [chromium-style] Classes that are ref-counted should have destructors that are declared protected or private.
  ~GbmDevice() override;
  ^
../../ui/ozone/platform/dri/gbm_device.h:14:19: note: [chromium-style] 'GbmDevice' inherits from 'ui::DrmDevice' here
class GbmDevice : public DrmDevice {
                  ^
../../ui/ozone/platform/dri/drm_device.h:41:32: note: [chromium-style] 'DrmDevice' inherits from 'base::RefCountedThreadSafe<DrmDevice>' here
class OZONE_EXPORT DrmDevice : public base::RefCountedThreadSafe<DrmDevice> {

BUG=none

Committed: https://crrev.com/a01795d72ee7d0f5b1d5acdcfcc67918b0e4d4c1
Cr-Commit-Position: refs/heads/master@{#318899}

[vignatti (out of this project), 2015-03-03 16:53:27]

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

[vignatti (out of this project), 2015-03-03 16:53:28]

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

[vignatti (out of this project), 2015-03-03 16:54:10]

PTAL.

[dnicoara, 2015-03-03 16:55:40]

The CQ bit was checked by dnicoara@chromium.org

[dnicoara, 2015-03-03 16:55:41]

lgtm

[commit-bot: I haz the power, 2015-03-03 16:56:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/975773002/1

[commit-bot: I haz the power, 2015-03-03 17:32:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-03 17:32:43]

Patchset 1 (id:??) landed as
https://crrev.com/a01795d72ee7d0f5b1d5acdcfcc67918b0e4d4c1
Cr-Commit-Position: refs/heads/master@{#318899}