Extract DeclarativeUserScriptManager from ExtensionSystem.

Extract DeclarativeUserScriptManager from ExtensionSystem.

This patch removes declarative_user_script_manager accessor from ExtensionSystem.
DeclarativeUserScriptManager is now a browser context keyed service.

Committed: https://crrev.com/6b9c265cac013bab0acc7b7dd7c11e6a1e5e71f8
Cr-Commit-Position: refs/heads/master@{#330418}

[juncai, 2015-05-15 20:18:24]

juncai@chromium.org changed reviewers:
+ reillyg@chromium.org, scheib@chromium.org

[juncai, 2015-05-15 20:18:25]

Hi, please review this patch. Thanks.

[juncai, 2015-05-15 20:48:48]

juncai@chromium.org changed reviewers:
- scheib@chromium.org

[Reilly Grant (use Gerrit), 2015-05-15 22:25:48]

reillyg@chromium.org changed reviewers:
+ scheib@chromium.org
- reillyg@chromium.org

[Reilly Grant (use Gerrit), 2015-05-15 22:26:02]

reillyg@chromium.org changed reviewers:
+ reillyg@chromium.org

[Reilly Grant (use Gerrit), 2015-05-15 22:26:02]

Round-robining this one to Vince.

[scheib, 2015-05-18 18:09:21]

LGTM,

I changed the description text slightly:

From:
"""
This patch removes declarative_user_script_manager accessor from
ExtensionSystem.
It can be its own browser context keyed service.
It can be built by its new factory.
"""

To:
"""
This patch removes declarative_user_script_manager accessor from
ExtensionSystem.
DeclarativeUserScriptManager is now a browser context keyed service.
"""

[juncai, 2015-05-18 18:15:02]

The CQ bit was checked by juncai@chromium.org

[commit-bot: I haz the power, 2015-05-18 18:16:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1132113008/40001

[commit-bot: I haz the power, 2015-05-18 21:00:31]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-05-18 22:43:19]

Patchset 3 (id:??) landed as
https://crrev.com/6b9c265cac013bab0acc7b7dd7c11e6a1e5e71f8
Cr-Commit-Position: refs/heads/master@{#330418}