[Extension] Protect all installed extension from extension storage GC

chrome/browser/extensions/extension_garbage_collector.cc

Index: chrome/browser/extensions/extension_garbage_collector.cc
diff --git a/chrome/browser/extensions/extension_garbage_collector.cc b/chrome/browser/extensions/extension_garbage_collector.cc
index 9ed6405a641f0ce35233cf9a39faf7e34ad25ca3..df33b09902e305dfc18c67462c47232b1d968d0e 100644
--- a/chrome/browser/extensions/extension_garbage_collector.cc
+++ b/chrome/browser/extensions/extension_garbage_collector.cc
@@ -220,10 +220,10 @@ void ExtensionGarbageCollector::GarbageCollectIsolatedStorageIfNeeded() {
 
   scoped_ptr<base::hash_set<base::FilePath> > active_paths(
       new base::hash_set<base::FilePath>());
-  const ExtensionSet& extensions =
-      ExtensionRegistry::Get(context_)->enabled_extensions();
-  for (ExtensionSet::const_iterator iter = extensions.begin();
-       iter != extensions.end();
+  scoped_ptr<ExtensionSet> extensions =
+      ExtensionRegistry::Get(context_)->GenerateInstalledExtensionsSet();

[Devlin, 2014/04/23 21:16:53]

It's a shame we have to keep around storage for all these extensions, since some
of them might actually stay disabled indefinitely, but it's probably worse to
get rid of it prematurely.  What we could use is a disable time, and if they're
disabled, for, say, > 7 days, delete storage, but I don't think we have anything
like that (do we, Yoyo?).

That said, I think we probably _should_ still delete storage of any extensions
that wind up on the Blacklist.  So only include Enabled, Disabled, and
Terminated.

[Marijn Kruisselbrink, 2014/04/23 23:09:51]

It still feels wrong to delete data of an app just because the app is
disabled... Suppose somebody only uses an app once a month, an update with
increased permissions might cause the app to be disabled, and the user won't
necessarily notice or care to re-enable the app until the next time it is used.
If a user really wants to get rid of data they can always just uninstall the
app, but doing so automatically just seems wrong to me.
I'm not sure we really should do that immediately either. Right now putting an
extension on a blacklist is something that is reversible. If we immediately
delete all its data this is no longer the case. So I don't think we should treat
this any different than otherwise disabled extensions.

[Devlin, 2014/04/23 23:21:06]

Hmm... maybe I need more knowledge about what goes into isolated storage.  I
thought it was a very small (usually unimportant) amount, and that most data was
stored in either prefs or through the chrome.storage API (which this shouldn't
affect) -- which would mean that cleaning up isolated storage isn't a big deal. 
What is it, exactly, that goes into isolated storage?

(By the way, I don't feel strongly about this, so don't feel blocked on my
review).

+  for (ExtensionSet::const_iterator iter = extensions->begin();
+       iter != extensions->end();
        ++iter) {
     if (AppIsolationInfo::HasIsolatedStorage(iter->get())) {
       active_paths->insert(