Rewire the local sync switches through the pref store.

components/sync/base/sync_prefs.cc

Index: components/sync/base/sync_prefs.cc
diff --git a/components/sync/base/sync_prefs.cc b/components/sync/base/sync_prefs.cc
index 63eab9182fca9b988fe25644c576f8eb55de92a5..e0adcb38606f0a19b0705b1dc796ddc2d8847481 100644
--- a/components/sync/base/sync_prefs.cc
+++ b/components/sync/base/sync_prefs.cc
@@ -86,6 +86,8 @@ void SyncPrefs::RegisterProfilePrefs(
       prefs::kSyncPassphraseEncryptionTransitionInProgress, false);
   registry->RegisterStringPref(prefs::kSyncNigoriStateForPassphraseTransition,
                                std::string());
+  registry->RegisterBooleanPref(prefs::kEnableLocalSyncBackend, false);
+  registry->RegisterFilePathPref(prefs::kLocalSyncBackendDir, base::FilePath());
 }
 
 void SyncPrefs::AddSyncPrefObserver(SyncPrefObserver* sync_pref_observer) {
@@ -546,4 +548,12 @@ void SyncPrefs::GetNigoriSpecificsForPassphraseTransition(
   }
 }
 
+bool SyncPrefs::IsLocalSyncEnabled() const {
+  return pref_service_->GetBoolean(prefs::kEnableLocalSyncBackend);
+}
+
+base::FilePath SyncPrefs::GetLocalSyncBackendDir() const {
+  return pref_service_->GetFilePath(prefs::kLocalSyncBackendDir);
+}
+
 }  // namespace syncer