Remove unnecessary #includes in system_tray.cc and tray_user_unittest.cc.

Remove unnecessary #includes in system_tray.cc and tray_user_unittest.cc.

After the landing https://codereview.chromium.org/184113005,
system_tray.cc and tray_user_unittest.cc don't need the command line
switch related headers anymore. So we can remove these.

BUG=348133
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=277894

[Sungmann Cho, 2014-06-16 21:14:34]

Please take a look. Thanks!

[sadrul, 2014-06-17 17:16:29]

lgtm

Thanks for doing the cleanup. But my suggestion would be to do such cleanup in a
larger number of files in the same module in a single CL, so that the review
load is smaller.

[Sungmann Cho, 2014-06-17 18:42:27]

On 2014/06/17 17:16:29, sadrul wrote:
> lgtm
> 
> Thanks for doing the cleanup. But my suggestion would be to do such cleanup in
a
> larger number of files in the same module in a single CL, so that the review
> load is smaller.

OK. Got it. Thanks!

[Sungmann Cho, 2014-06-17 18:42:36]

The CQ bit was checked by sungmann.cho@navercorp.com

[commit-bot: I haz the power, 2014-06-17 18:44:31]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sungmann.cho@navercorp.com/338133002/1

[commit-bot: I haz the power, 2014-06-17 23:14:27]

Change committed as 277894