Move ExtensionService::ReportExtensionLoadError to ExtensionErrorReporter

Move ExtensionService::ReportExtensionLoadError to ExtensionErrorReporter

This isn't a huge improvement, because ExtensionErrorReporter has its own
faults, but it at least centers all the logic in the same module, and handles
a 2.5 year TODO from aa. This will (hopefully) make it easier when we continue
to refactor this logic.
BUG=351891
TBR=finnur@chromium.org (for one line change to web_ui)

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=267562

[Yoyo Zhou, 2014-04-30 17:21:13]

LGTM

[Devlin, 2014-05-01 15:51:05]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2014-05-01 15:51:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/263643005/1

[commit-bot: I haz the power, 2014-05-01 15:59:43]

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

[commit-bot: I haz the power, 2014-05-01 15:59:44]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium

[Devlin, 2014-05-01 16:38:26]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2014-05-01 16:39:15]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/263643005/1

[commit-bot: I haz the power, 2014-05-01 17:26:14]

Change committed as 267562