Clear the ephemeral app cache from Clear Browsing Data

chrome/browser/apps/ephemeral_app_service.cc

Index: chrome/browser/apps/ephemeral_app_service.cc
diff --git a/chrome/browser/apps/ephemeral_app_service.cc b/chrome/browser/apps/ephemeral_app_service.cc
index da4a5d19ab9b5b79956e6ffd82be4a38ea52e4de..da8d4a592200c5e8b9ba2d3fed745f5ed1490c41 100644
--- a/chrome/browser/apps/ephemeral_app_service.cc
+++ b/chrome/browser/apps/ephemeral_app_service.cc
@@ -71,6 +71,40 @@ EphemeralAppService::EphemeralAppService(Profile* profile)
 EphemeralAppService::~EphemeralAppService() {
 }
 
+void EphemeralAppService::ClearCachedApps() {
+  // Cancel any pending garbage collects.
+  garbage_collect_apps_timer_.Stop();
+
+  scoped_ptr<ExtensionSet> extensions =
+      extensions::ExtensionRegistry::Get(profile_)
+          ->GenerateInstalledExtensionsSet();
+  ExtensionPrefs* prefs = ExtensionPrefs::Get(profile_);
+  DCHECK(prefs);
+
+  ExtensionService* service =
+      ExtensionSystem::Get(profile_)->extension_service();
+  DCHECK(service);
+
+  for (ExtensionSet::const_iterator it = extensions->begin();
+       it != extensions->end();
+       ++it) {
+    std::string extension_id = (*it)->id();
+    if (!prefs->IsEphemeralApp(extension_id) ||
+        !service->GetInstalledExtension(extension_id)) {

[tapted, 2014/07/11 01:16:36]

I think GetInstalledExtension(..) should return true for everything in
GenerateInstalledExtensionsSet - maybe DCHECK? (also note GetInstalledExtension
is marked deprecated)

unless uninstalling one extension can cascade and trigger an uninstall of
another..

[tmdiep, 2014/07/11 02:28:31]

There is a CHECK in ExtensionService::UninstallExtension() which makes me
nervous, so this is just a sanity check. If prefs->IsEphemeralApp() returns
true, there *should* be an extension in the registry, so I made this a DCHECK.

SharedModuleService::OnExtensionUninstalled() is a current case of cascading
uninstalls. That shouldn't apply here, but just in case there will be
dependencies between ephemeral apps in the future...

+      continue;
+    }
+
+    // Do not remove apps that are running.
+    if (!extensions::util::IsExtensionIdle(extension_id, profile_))
+      continue;
+
+    service->UninstallExtension(
+        extension_id,
+        ExtensionService::UNINSTALL_REASON_ORPHANED_EPHEMERAL_EXTENSION,
+        NULL);
+  }
+}
+
 void EphemeralAppService::Observe(
     int type,
     const content::NotificationSource& source,
@@ -189,11 +223,14 @@ void EphemeralAppService::GarbageCollectApps() {
   ExtensionService* service =
       ExtensionSystem::Get(profile_)->extension_service();
   DCHECK(service);
-  // Execute the replacement policies and remove apps marked for deletion.
+  // Execute the eviction policies and remove apps marked for deletion.
   if (!app_launch_times.empty()) {
     GetAppsToRemove(app_count, app_launch_times, &remove_app_ids);
     for (std::set<std::string>::const_iterator id = remove_app_ids.begin();
          id != remove_app_ids.end(); ++id) {
+      if (!service->GetInstalledExtension(*id))

[tapted, 2014/07/11 01:16:36]

I don't think I've wrapped my head around this bit. Can you add a comment?  My
interpretation: since IsExtensionIdle returns `false` for extensions that it
can't find we can end up here with an extension that's been uninstalled. But
then I'm not sure why you don't need to clear out something else, or do
`--app_count` before continuing. And I'm not sure why it would have appeared in
the set generated by GenerateInstalledExtensionsSet in the first place.

Also would this apply to things uninstalled by sync as well as clear browsing
data?

(also GetInstalledExtension is marked deprecated - use the alternative?)

[tmdiep, 2014/07/11 02:28:31]

Same reason as above - in case of cascading uninstalls.

Good point about the app count. I don't really need to maintain it here, 
OnExtensionUninstalled() will handle it. 
Ephemeral apps don't really get synced. But suppose you have an ephemeral app on
device A, you installed and uninstalled it on device B.
- If both the install and uninstall messages got through - the app gets promoted
and uninstalled (this case is half tested in browser tests - the install from
sync part).
- If only the uninstall message got through for some reason, I think the
ephemeral app would be removed, which is fine. I'll need to add a browser test
for this.
Done.

+        continue;
+
       if (service->UninstallExtension(
               *id,
               ExtensionService::UNINSTALL_REASON_ORPHANED_EPHEMERAL_EXTENSION,