Revert "Removes MediaDecoderJob virtual method call from destructor."

Revert "Removes MediaDecoderJob virtual method call from destructor."

This reverts commit 6a1f7b511cdcb590bcebb8371e880908fe592a22.

The above commit was only intended for cherry-picking to M37/M38 branches.

R=qinmin@chromium.org,ycheo@chromium.org
BUG=

Committed: https://crrev.com/69b99efe022a4e44384522da1c117364e9d1dc4d
Cr-Commit-Position: refs/heads/master@{#299312}

[qinmin, 2014-10-13 16:19:51]

lgtm

[gunsch, 2014-10-13 16:22:15]

The CQ bit was checked by gunsch@chromium.org

[commit-bot: I haz the power, 2014-10-13 16:23:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/650223002/1

[commit-bot: I haz the power, 2014-10-13 16:55:47]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-13 16:55:48]

Try jobs failed on following builders:
  win_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu_triggered...)

[gunsch, 2014-10-13 16:58:14]

The CQ bit was checked by gunsch@chromium.org

[commit-bot: I haz the power, 2014-10-13 16:59:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/650223002/1

[commit-bot: I haz the power, 2014-10-13 17:15:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-13 17:15:46]

Patchset 1 (id:??) landed as
https://crrev.com/69b99efe022a4e44384522da1c117364e9d1dc4d
Cr-Commit-Position: refs/heads/master@{#299312}