Fix build dependencies in src/extensions

Fix build dependencies in src/extensions

* lazy_background_task_queue_unittest.cc uses keyed_service/content directly
so make dependency explicit.
* I missed the GN build file when adding extensions_test.h/cc

BUG=none
TEST=compiles

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287471

[James Cook, 2014-08-04 21:19:15]

rockot, PTAL

tfarina, FYI

[Ken Rockot(use gerrit already), 2014-08-04 21:30:29]

lgtm

[James Cook, 2014-08-04 21:44:29]

The CQ bit was checked by jamescook@chromium.org

[commit-bot: I haz the power, 2014-08-04 21:45:39]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamescook@chromium.org/432433003/1

[commit-bot: I haz the power, 2014-08-04 23:10:32]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/37230)
  linux_chromium_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  win_chromium_x64_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[commit-bot: I haz the power, 2014-08-04 23:16:51]

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

[commit-bot: I haz the power, 2014-08-04 23:16:51]

Try jobs failed on following builders:
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/37271)

[James Cook, 2014-08-04 23:36:02]

The CQ bit was checked by jamescook@chromium.org

[commit-bot: I haz the power, 2014-08-04 23:38:34]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamescook@chromium.org/432433003/1

[commit-bot: I haz the power, 2014-08-05 01:38:40]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/37283)

[commit-bot: I haz the power, 2014-08-05 01:45:31]

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

[commit-bot: I haz the power, 2014-08-05 01:45:32]

Try jobs failed on following builders:
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/37325)

[James Cook, 2014-08-05 01:51:23]

The CQ bit was checked by jamescook@chromium.org

[commit-bot: I haz the power, 2014-08-05 01:53:51]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamescook@chromium.org/432433003/1

[commit-bot: I haz the power, 2014-08-05 06:40:01]

Change committed as 287471

[tfarina, 2014-08-05 14:11:20]

lgtm

thanks