Fix crash on referencing deleted SignedInDevicesManager observer

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

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/api/signed_in_devices/signed_in_devices_manager.h"
 
 #include <string>
 #include <vector>
 
 #include "base/lazy_instance.h"
@@ skipping 97 matching lines @@
   if (router) {
     router->RegisterObserver(
         this, api::signed_in_devices::OnDeviceInfoChange::kEventName);
   }
 
   // Register for unload event so we could clear all our listeners when
   // extensions have unloaded.
   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) {
   for (ScopedVector<SignedInDevicesChangeObserver>::const_iterator it =
            change_observers_.begin();
            it != change_observers_.end();
            ++it) {
     if ((*it)->extension_id() == details.extension_id) {
       DCHECK(false) <<"OnListenerAded fired twice for same extension";
       return;
@@ skipping 24 matching lines @@
 }
 
 void SignedInDevicesManager::OnExtensionUnloaded(
     content::BrowserContext* browser_context,
     const Extension* extension,
     UnloadedExtensionInfo::Reason reason) {
   RemoveChangeObserverForExtension(extension->id());
 }
 
 }  // namespace extensions