Add migration code to change existing domain scoped content settings to be origin scoped

components/syncable_prefs/pref_model_associator.cc

Index: components/syncable_prefs/pref_model_associator.cc
diff --git a/components/syncable_prefs/pref_model_associator.cc b/components/syncable_prefs/pref_model_associator.cc
index 4cbdd558881022f6e5abb32c4cd5e53da6e8baf8..9e3d4722324050e6dbad476d3da12b1662e39acf 100644
--- a/components/syncable_prefs/pref_model_associator.cc
+++ b/components/syncable_prefs/pref_model_associator.cc
@@ -7,6 +7,8 @@
 #include <utility>
 
 #include "base/auto_reset.h"
+#include "base/bind.h"
+#include "base/callback.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/location.h"
@@ -54,6 +56,8 @@ sync_pb::PreferenceSpecifics* GetMutableSpecifics(
 
 }  // namespace
 
+base::Closure syncable_prefs::PrefModelAssociator::migrate_call_back_;
+
 PrefModelAssociator::PrefModelAssociator(
     const PrefModelAssociatorClient* client,
     syncer::ModelType type)
@@ -157,6 +161,17 @@ void PrefModelAssociator::InitPrefAndAssociate(
   // we'll send the new user controlled value to the syncer.
 }
 
+// static
+void PrefModelAssociator::SetMergeDataFinishedCallback(
+    const base::Closure& callback) {
+  migrate_call_back_ = callback;
+}
+
+// static
+void PrefModelAssociator::ResetMergeDataFinishedCallback() {
+  migrate_call_back_.Reset();
+}
+
 syncer::SyncMergeResult PrefModelAssociator::MergeDataAndStartSyncing(
     syncer::ModelType type,
     const syncer::SyncDataList& initial_sync_data,
@@ -206,7 +221,9 @@ syncer::SyncMergeResult PrefModelAssociator::MergeDataAndStartSyncing(
        ++pref_name_iter) {
     InitPrefAndAssociate(syncer::SyncData(), *pref_name_iter, &new_changes);
   }
-
+  if (!migrate_call_back_.is_null()) {
+    migrate_call_back_.Run();
+  }
   // Push updates to sync.
   merge_result.set_error(
       sync_processor_->ProcessSyncChanges(FROM_HERE, new_changes));