Refactor external_install_ui

Refactor external_install_ui

Refactors ExternalInstallUI to have determinate lifetimes.
This is likely the first of multiple patches targeting this area of code; the
next one will concentrate on pulling the related logic out of ExtensionService.

BUG=378042
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=273982

[Devlin, 2014-05-28 19:42:36]

Yoyo, please take a look when you can.  In particular, please do let me know if
this is an improvement over the original for lifetime management/readability. 
To me, it definitely seems like it is, but then again, I wrote it (so I'm bound
to understand it).

[Yoyo Zhou, 2014-05-29 23:20:24]

mostly LGTM, one comment though

https://chromiumcodereview.appspot.com/300853008/diff/60001/chrome/browser/ex...
File chrome/browser/extensions/external_install_error.h (right):

https://chromiumcodereview.appspot.com/300853008/diff/60001/chrome/browser/ex...
chrome/browser/extensions/external_install_error.h:32: // initializted and
removing itself from the GlobalErrorService upon
typo: initialized

https://chromiumcodereview.appspot.com/300853008/diff/60001/chrome/browser/ex...
File chrome/browser/extensions/external_install_manager.cc (right):

https://chromiumcodereview.appspot.com/300853008/diff/60001/chrome/browser/ex...
chrome/browser/extensions/external_install_manager.cc:75: void
ExternalInstallManager::OnExtensionUnloaded(
Does this handle the removal of a disabled extension? (This used to observe
NOTIFICATION_EXTENSION_REMOVED)

[Devlin, 2014-05-30 16:14:44]

https://codereview.chromium.org/300853008/diff/60001/chrome/browser/extension...
File chrome/browser/extensions/external_install_error.h (right):

https://codereview.chromium.org/300853008/diff/60001/chrome/browser/extension...
chrome/browser/extensions/external_install_error.h:32: // initializted and
removing itself from the GlobalErrorService upon
On 2014/05/29 23:20:24, Yoyo Zhou wrote:
> typo: initialized

Done.

https://codereview.chromium.org/300853008/diff/60001/chrome/browser/extension...
File chrome/browser/extensions/external_install_manager.cc (right):

https://codereview.chromium.org/300853008/diff/60001/chrome/browser/extension...
chrome/browser/extensions/external_install_manager.cc:75: void
ExternalInstallManager::OnExtensionUnloaded(
On 2014/05/29 23:20:24, Yoyo Zhou wrote:
> Does this handle the removal of a disabled extension? (This used to observe
> NOTIFICATION_EXTENSION_REMOVED)

Dang, it doesn't.  Guess we have to go back to the NotificationObserver.  Done.

[Devlin, 2014-05-30 16:14:47]

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

[commit-bot: I haz the power, 2014-05-30 16:17:58]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/300853008/...

[commit-bot: I haz the power, 2014-05-31 01:36:25]

Change committed as 273982