Fix crash on referencing deleted SignedInDevicesManager observer

chrome/browser/extensions/api/signed_in_devices/signed_in_devices_manager.cc

Index: chrome/browser/extensions/api/signed_in_devices/signed_in_devices_manager.cc
diff --git a/chrome/browser/extensions/api/signed_in_devices/signed_in_devices_manager.cc b/chrome/browser/extensions/api/signed_in_devices/signed_in_devices_manager.cc
index 2dcc91cc0298313ad383637e693e7d2deebbfc9b..37219e0d80708218699e376637a1479e9d98808a 100644
--- a/chrome/browser/extensions/api/signed_in_devices/signed_in_devices_manager.cc
+++ b/chrome/browser/extensions/api/signed_in_devices/signed_in_devices_manager.cc
@@ -115,7 +115,13 @@ SignedInDevicesManager::SignedInDevicesManager(content::BrowserContext* context)
   extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
 }
 
-SignedInDevicesManager::~SignedInDevicesManager() {}
+SignedInDevicesManager::~SignedInDevicesManager() {
+  if (profile_) {

[Devlin, 2015/03/09 16:35:43]

Will profile_ ever be null?  We don't seem to check it in the constructor...

[Rafał Chłodnicki, 2015/03/09 20:46:43]

But there are two constructors. One is for testing and has null profile.

+    extensions::EventRouter* router = extensions::EventRouter::Get(profile_);

[Devlin, 2015/03/09 16:35:43]

nit: remove extensions:: prefix (you're in the extensions namespace here).

[Rafał Chłodnicki, 2015/03/09 20:46:43]

Done.

+    if (router)
+      router->UnregisterObserver(this);

[Devlin, 2015/03/09 16:35:43]

Shame we can't use a ScopedObserver for this... ah well.  (No action required.)

+  }
+}
 
 void SignedInDevicesManager::OnListenerAdded(
     const EventListenerInfo& details) {