Move ObserverList to base namespace.

Move ObserverList to base namespace.

Moves ObserverList and related classes to the base namespace.

ObserverList[ThreadSafe] maintains a using statement to avoid having to update all users atomically. Users of ObserverListBase are updated in this patch.

BUG=
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/5a1613dcb83ac548403796eb1320d17dad52ccd8
Cr-Commit-Position: refs/heads/master@{#332347}

[brettw, 2015-06-01 17:41:43]

brettw@chromium.org changed reviewers:
+ sky@chromium.org

[brettw, 2015-06-01 17:41:49]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-01 17:43:22]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1152983004/1

[commit-bot: I haz the power, 2015-06-01 17:56:31]

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

[commit-bot: I haz the power, 2015-06-01 17:56:33]

Dry run: Try jobs failed on following builders:
  android_chromium_gn_compile_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)
  linux_chromium_gn_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[sky, 2015-06-01 18:12:24]

LGTM

[brettw, 2015-06-01 18:24:47]

The CQ bit was checked by brettw@chromium.org

[brettw, 2015-06-01 18:24:48]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org
Link to the patchset: https://codereview.chromium.org/1152983004/#ps20001
(title: " ")

[commit-bot: I haz the power, 2015-06-01 18:26:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1152983004/20001

[commit-bot: I haz the power, 2015-06-01 18:46:32]

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

[commit-bot: I haz the power, 2015-06-01 18:46:34]

Try jobs failed on following builders:
  win_chromium_x64_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[brettw, 2015-06-01 19:16:30]

The CQ bit was checked by brettw@chromium.org

[brettw, 2015-06-01 19:16:30]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org
Link to the patchset: https://codereview.chromium.org/1152983004/#ps40001
(title: " ")

[commit-bot: I haz the power, 2015-06-01 19:21:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1152983004/40001

[brettw, 2015-06-01 20:07:17]

The CQ bit was checked by brettw@chromium.org

[brettw, 2015-06-01 20:07:18]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org
Link to the patchset: https://codereview.chromium.org/1152983004/#ps60001
(title: " ")

[commit-bot: I haz the power, 2015-06-01 20:12:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1152983004/60001

[commit-bot: I haz the power, 2015-06-01 23:44:39]

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

[commit-bot: I haz the power, 2015-06-01 23:44:41]

Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[brettw, 2015-06-02 04:22:18]

The CQ bit was checked by brettw@chromium.org

[commit-bot: I haz the power, 2015-06-02 04:22:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1152983004/60001

[commit-bot: I haz the power, 2015-06-02 05:34:54]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-06-02 05:35:53]

Patchset 4 (id:??) landed as
https://crrev.com/5a1613dcb83ac548403796eb1320d17dad52ccd8
Cr-Commit-Position: refs/heads/master@{#332347}