Remove InstallTracker's extension installed, uninstalled observers.

Remove InstallTracker's extension [un]installed observer.
Since ExtensionRegistry provide canonical way, use ExtensionRegistry instead.

R=kalman@chromium.org, xiyuan@chromium.org
BUG=374353
TEST=unit_tests

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=276474

[not at google - send to devlin, 2014-06-10 18:12:41]

lgtm

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
File chrome/browser/extensions/install_tracker.h (right):

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
chrome/browser/extensions/install_tracker.h:47: //                You might want
to use ExtensionRegistryObserver.
s/You might want to //.

I.e. just "For extension [un]load and [un]install use
ExtensionRegistryObserver".

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
File chrome/browser/extensions/shared_module_service.cc (left):

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
chrome/browser/extensions/shared_module_service.cc:169:
InstallTracker::Get(context_)->RemoveObserver(this);
so.... it does seem like this is safe to remove, because SharedModuleService is
owned by ExtensionService, which has a shorter lifetime than ExtensionRegistry.

so, hoping for the best here - but if this is a problem then we may need to add
back the OnShutdown behaviour.

[limasdf, 2014-06-11 00:26:00]

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
File chrome/browser/extensions/install_tracker.h (right):

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
chrome/browser/extensions/install_tracker.h:47: //                You might want
to use ExtensionRegistryObserver.
On 2014/06/10 18:12:41, kalman wrote:
> s/You might want to //.
> 
> I.e. just "For extension [un]load and [un]install use
> ExtensionRegistryObserver".

Thank you.

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
File chrome/browser/extensions/shared_module_service.cc (left):

https://codereview.chromium.org/323763002/diff/60001/chrome/browser/extension...
chrome/browser/extensions/shared_module_service.cc:169:
InstallTracker::Get(context_)->RemoveObserver(this);
On 2014/06/10 18:12:41, kalman wrote:
> so.... it does seem like this is safe to remove, because SharedModuleService
is
> owned by ExtensionService, which has a shorter lifetime than
ExtensionRegistry.
> 
> so, hoping for the best here - but if this is a problem then we may need to
add
> back the OnShutdown behaviour.

yep, please let me know if there's problem about this.

[limasdf, 2014-06-11 00:26:06]

The CQ bit was checked by limasdf@gmail.com

[commit-bot: I haz the power, 2014-06-11 00:27:48]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/limasdf@gmail.com/323763002/100001

[limasdf, 2014-06-11 01:21:31]

The CQ bit was unchecked by limasdf@gmail.com

[limasdf, 2014-06-11 01:22:42]

Added @xiyuan as the owner of ui/app_list
Xiyuan, Could you take a look at ui/app_list?

[limasdf, 2014-06-11 11:06:55]

The CQ bit was checked by limasdf@gmail.com

[commit-bot: I haz the power, 2014-06-11 11:09:16]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/limasdf@gmail.com/323763002/120001

[limasdf, 2014-06-11 11:16:22]

On 2014/06/11 11:09:16, I haz the power (commit-bot) wrote:
> CQ is trying da patch. Follow status at
>  https://chromium-status.appspot.com/cq/limasdf@gmail.com/323763002/120001

Added @xiyuan as the owner of ui/app_list
Xiyuan, Could you take a look at ui/app_list?

[commit-bot: I haz the power, 2014-06-11 17:11:08]

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

[xiyuan, 2014-06-11 17:12:05]

app_list/* LGTM

[commit-bot: I haz the power, 2014-06-11 19:32:40]

Change committed as 276474