No longer keep a lingering reference to TypedUrlDataTypeController after PSS exits

chrome/browser/sync/profile_sync_service.cc

 // Copyright (c) 2012 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/sync/profile_sync_service.h"
 
 #include <cstddef>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 138 matching lines @@
   if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_BETA) {
     sync_service_url_ = GURL(kSyncServerUrl);
   }
 #endif
 }
 
 ProfileSyncService::~ProfileSyncService() {
   sync_prefs_.RemoveSyncPrefObserver(this);
   Shutdown();
+#if defined(NDEBUG)
+  // Make sure there are no dangling references to the DataTypeControllers.
+  for (browser_sync::DataTypeController::TypeMap::const_iterator iter =
+           data_type_controllers_.begin(); iter != data_type_controllers_.end();
+       ++iter) {
+    DCHECK(iter->second->HasOneRef())

[Nicolas Zea, 2012/05/16 22:40:58]

This does not hold true for non-UI thread datatypes implementing the new API,
where not blocking shutdown was one of our goals. In those cases, we don't
bother to wait for them to finish stopping, since we have an disconnect-able
interface that they must go through to interact with sync.

In other words, once DTC::Stop() is called, the datatype won't be able to
interact with the PSS or anything within sync, letting us continue without
blocking shutdown. The DTC ma have running/pending tasks on the datatype's
thread that don't execute until after Stop(), but we ensure correctness.

What do you think about, at least for new DTC's, just making it clear that no
member of the DTC should rely on the profile being around after Stop is called
(either by clearing these members during Stop() or by ensuring they are POD's)?

+        << "DataTypeController will outlive ProfileSyncService: "
+        << iter->second->name();
+  }
+#endif
 }
 
 bool ProfileSyncService::AreCredentialsAvailable() {
   if (IsManaged()) {
     return false;
   }
 
   // If we have start suppressed, then basically just act like we have no
   // credentials (login is required to fix this, since we need the user's
   // passphrase to encrypt/decrypt anyway).
@@ skipping 1498 matching lines @@
   // See http://stackoverflow.com/questions/6224121/is-new-this-myclass-undefined-behaviour-after-directly-calling-the-destru.
   ProfileSyncService* old_this = this;
   this->~ProfileSyncService();
   new(old_this) ProfileSyncService(
       new ProfileSyncComponentsFactoryImpl(profile,
                                            CommandLine::ForCurrentProcess()),
       profile,
       signin,
       behavior);
 }