Draft change to use base::Closure instead of PrefObserver in PrefChangeRegistrar.

base/prefs/public/pref_change_registrar.cc

 // Copyright (c) 2010 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 "base/prefs/public/pref_change_registrar.h"
 
+#include "base/bind.h"
 #include "base/logging.h"
+#include "base/prefs/public/pref_observer.h"
 #include "base/prefs/public/pref_service_base.h"
 
 PrefChangeRegistrar::PrefChangeRegistrar() : service_(NULL) {}
 
 PrefChangeRegistrar::~PrefChangeRegistrar() {
   // If you see an invalid memory access in this destructor, this
   // PrefChangeRegistrar might be subscribed to an OffTheRecordProfileImpl that
   // has been destroyed. This should not happen any more but be warned.
   // Feel free to contact battre@chromium.org in case this happens.
   RemoveAll();
 }
 
 void PrefChangeRegistrar::Init(PrefServiceBase* service) {
   DCHECK(IsEmpty() || service_ == service);
   service_ = service;
 }
 
 void PrefChangeRegistrar::Add(const char* path, PrefObserver* obs) {
+  return Add(path, base::Bind(&PrefObserver::OnPreferenceChanged,
+                              base::Unretained(obs), service_, path));
+}
+
+void PrefChangeRegistrar::Add(const char* path, const base::Closure& obs) {
   if (!service_) {
     NOTREACHED();
     return;
   }
   ObserverRegistration registration(path, obs);
   if (observers_.find(registration) != observers_.end()) {
     NOTREACHED();
     return;
   }
   observers_.insert(registration);
   service_->AddPrefObserver(path, obs);
 }
 
 void PrefChangeRegistrar::Remove(const char* path, PrefObserver* obs) {
+  // Need to bind the callback the exact same way, although it will
+  // never be called, so that it matches the callback bound via
+  // AddPrefObserver.
+  return Remove(path, base::Bind(&PrefObserver::OnPreferenceChanged,
+                                 base::Unretained(obs), service_, path));

[Mattias Nissler (ping if slow), 2012/11/06 13:26:48]

Hm, comparing callbacks... not sure whether that's a good idea.

In the discussion with battre@ last week, we figured we'd probably change the
interface here to allow only a single callback per pref (we thought that's a
reasonable restriction, haven't checked all consumers though). Also we'd change
the model to not forward the callback registration with PrefService, but store a
std::map<std::string, base::Closure> in PrefChangeRegistrar. We would then have
PrefService keep a list of PrefChangeRegistrars, which it forwards pref change
events to, and PrefChangeRegistrar would figure out the callback to invoke using
its map. Remove would not take a closure as a parameter. WDYT? Makes sense?

+}
+
+void PrefChangeRegistrar::Remove(const char* path, const base::Closure& obs) {
   if (!service_) {
     NOTREACHED();
     return;
   }
   ObserverRegistration registration(path, obs);
   std::set<ObserverRegistration>::iterator it =
        observers_.find(registration);
   if (it == observers_.end()) {
     NOTREACHED();
     return;
@@ skipping 28 matching lines @@
 bool PrefChangeRegistrar::IsManaged() {
   for (std::set<ObserverRegistration>::const_iterator it = observers_.begin();
        it != observers_.end(); ++it) {
     const PrefServiceBase::Preference* pref =
         service_->FindPreference(it->first.c_str());
     if (pref && pref->IsManaged())
       return true;
   }
   return false;
 }