[Sync] Switch Extension Settings DTC to use ProfilesyncComponentsFactory

chrome/browser/extensions/settings/settings_frontend.cc

Index: chrome/browser/extensions/settings/settings_frontend.cc
diff --git a/chrome/browser/extensions/settings/settings_frontend.cc b/chrome/browser/extensions/settings/settings_frontend.cc
index 6c5fbedf04e1f0785175002333943ab5e6c24e0c..4651644a0e868f1784b1c5aec380f8a997d46c16 100644
--- a/chrome/browser/extensions/settings/settings_frontend.cc
+++ b/chrome/browser/extensions/settings/settings_frontend.cc
@@ -161,6 +161,10 @@ class SettingsFrontend::BackendWrapper
             callback));
   }
 
+  SettingsBackend* GetBackend() const {

[not at google - send to devlin, 2012/02/16 22:58:44]

DCHECK(FILE thread).

[Nicolas Zea, 2012/02/23 00:27:58]

Done.

+    return backend_;
+  }
+
  private:
   friend class base::RefCountedThreadSafe<BackendWrapper>;
 
@@ -273,23 +277,22 @@ SettingsFrontend::~SettingsFrontend() {
   observers_->RemoveObserver(profile_observer_.get());
 }
 
-void SettingsFrontend::RunWithSyncableService(
-    syncable::ModelType model_type, const SyncableServiceCallback& callback) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  scoped_refptr<BackendWrapper> backend;
-  switch (model_type) {
+SyncableService* SettingsFrontend::GetBackendForSync(
+    syncable::ModelType type) const {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  std::map<settings_namespace::Namespace, BackendWrappers>::const_iterator
+      sync_backends = backends_.find(settings_namespace::SYNC);

[not at google - send to devlin, 2012/02/16 22:58:44]

How can this ever not find ::SYNC? The constructor populates it and I didn't
think it ever gets depopulated.

Is it so that backends_ has no chance of being mutated and thus implying thread
safety? I don't know if that follows, if it does then cool, maybe Fred will know
more about this (in any case I think the check below "if sync_backends ==
backends.end()" should be a DCHECK/CHECK).

Note that this class was designed to "live entirely" (from an interface
perspective) on the same thread, for brain-confidence of thread safety. It would
be nice for that not to change, but if it does, oh well.

[Nicolas Zea, 2012/02/23 00:27:58]

I was just being overcautious. Added a NOTREACHED in the else case.

[not at google - send to devlin, 2012/02/23 02:15:38]

DCHECK_NE(sync_backends, backends_.end()) would be more concise.

[Nicolas Zea, 2012/02/24 21:38:04]

Done.

+  if (sync_backends == backends_.end())
+    return NULL;
+  switch (type) {
     case syncable::APP_SETTINGS:
-      backend = backends_[settings_namespace::SYNC].app;
-      break;
-
+      return sync_backends->second.app->GetBackend();
     case syncable::EXTENSION_SETTINGS:
-      backend = backends_[settings_namespace::SYNC].extension;
-      break;
-
+      return sync_backends->second.extension->GetBackend();
     default:
       NOTREACHED();
+      return NULL;
   }
-  backend->RunWithBackend(base::Bind(&CallbackWithSyncableService, callback));
 }
 
 void SettingsFrontend::RunWithStorage(