Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/profiles/profile_keyed_base_factory.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/profiles/profile_keyed_base_factory.h"
 
+#include "chrome/browser/prefs/pref_registry_syncable.h"
+#include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_dependency_manager.h"
 
 ProfileKeyedBaseFactory::ProfileKeyedBaseFactory(
     const char* name, ProfileDependencyManager* manager)
     : dependency_manager_(manager)
 #ifndef NDEBUG
     , service_name_(name)
 #endif
 {
@@ skipping 52 matching lines @@
   // registration to happen at service creation time).
   //
   // Now that services are responsible for declaring their preferences, we have
   // to enforce a uniquenes check here because some tests create one profile and
   // multiple services of the same type attached to that profile (serially, not
   // parallel) and we don't want to register multiple times on the same profile.
   DCHECK(!profile->IsOffTheRecord());
 
   std::set<Profile*>::iterator it = registered_preferences_.find(profile);
   if (it == registered_preferences_.end()) {
-    RegisterUserPrefs(profile->GetPrefs());
+    PrefService* prefs = profile->GetPrefs();
+    PrefRegistrySyncable* registry = static_cast<PrefRegistrySyncable*>(
+        prefs->DeprecatedGetPrefRegistry());
+    RegisterUserPrefs(registry);
+    // A few registration functions still need the PrefService pointer
+    // (e.g. to clear preferences).
+    DeprecatedRegisterUserPrefs(prefs, registry);

[Mattias Nissler (ping if slow), 2013/02/06 17:53:33]

Yikes, hacks over hacks here. I'll have to think a bit more about registrations
coming from PKSs.

[Jói, 2013/02/07 14:52:32]

Yeah, when I ran into this I thought "oops" :)  But better to clean such things
up in separate smaller changes I think.   

I figured that for now, we'd be better off with a separate DeprecatedXyz method
that gets the PrefService parameter, rather than passing PrefService in the main
method, so that people don't start accidentally introducing more dependencies.

[Mattias Nissler (ping if slow), 2013/02/08 11:26:56]

So, I wonder whether we'd be better off if we just had all the PKSF that are
compiled in register their prefs when a profile initializes. Admittedly this
will register prefs that are not used (because the corresponding PKS is not
instantiated), but that's a price I'd be willing to pay.

     registered_preferences_.insert(profile);
   }
 }
 
 bool ProfileKeyedBaseFactory::ServiceRedirectedInIncognito() const {
   return false;
 }
 
 bool ProfileKeyedBaseFactory::ServiceHasOwnInstanceInIncognito() const {
   return false;
@@ skipping 17 matching lines @@
 
 bool ProfileKeyedBaseFactory::ArePreferencesSetOn(Profile* profile) const {
   return registered_preferences_.find(profile) !=
       registered_preferences_.end();
 }
 
 void ProfileKeyedBaseFactory::MarkPreferencesSetOn(Profile* profile) {
   DCHECK(!ArePreferencesSetOn(profile));
   registered_preferences_.insert(profile);
 }